Wikipedia:Citing sources

"WP:CITE" redirects here. For information on citing Wikipedia articles, see WP:CITEWIKI.

"WP:REF" redirects here. For the Reference Desk, see WP:REFDESK.

This page describes how to write citations in articles. Wikipedia's verifiability policy requires attribution for direct quotes and for material that is likely to be challenged. Any material that is challenged, and for which no source is provided within a reasonable time (or immediately if it's about a living person), may be removed by any editor. For information about the importance of using good sources in biographies of living persons, see the policy Wikipedia:Biographies of living persons.

If you don't know how to format a citation, provide as much information as you can, and others will help to write it correctly.

Use of terms

This guideline uses the terms citation and reference interchangeably. The source is the document (including webpages) that is being cited/referenced.

The terms Footnote and Note are also used interchangeably. There is no separate usage of the term "Endnote" because each Wikipedia article, like other HTML documents, is considered to be only one page even if it is displayed across several screens.

A common system of citation on Wikipedia is a footnote system, in which case all the above terms may be used interchangeably in some cases.

The terms Further Reading, External links or Bibliography are used as section headings in Wikipedia articles for lists of additional general texts on a topic for those interested, rather than for citations supporting the article.

When to cite sources

Main page: Wikipedia:When to cite

Wikipedia is by its very nature a work by people with widely different knowledge and skills. The reader needs to be assured that the material within it is reliable. The purpose of citing sources is:

• To ensure that the content of articles can be checked by any reader or editor.
• To show that your edit is not original research and to reduce editorial disputes.
• To avoid claims of plagiarism and copying.
• To help users find additional information on the topic.
• To ensure that material about living persons complies with biography policy.
• To improve the credibility of Wikipedia.

Wikipedia's criteria for featured articles (the standard to aim for) call for citations where appropriate. The following are examples of when it is likely to be appropriate. This list is not exhaustive, and each case must be dealt with on its merits.

When adding material that is challenged or likely to be challenged

Main page: Wikipedia:Verifiability

Wikipedia:Verifiability says: "All quotations and any material challenged or likely to be challenged should be attributed to a reliable, published source using an inline citation."

The need for citations is especially important when writing about opinions held on a particular issue. Avoid weasel words where possible, such as, "Some people say ..." Instead, make your writing verifiable: find a specific person or group who holds that opinion and give a citation to a reputable publication in which they express that opinion. Remember that Wikipedia is not a place for expressing your own opinions or for original research. Opinions, data and statistics, and statements based on someone's scientific work should be cited and attributed to their authors in the text.

When quoting someone

Main page: Wikipedia:Verifiability

You should always add a citation when quoting published material, and the citation should be placed directly after (or just before) the quotation, which should be enclosed within double quotation marks — "like this" — or single quotation marks if it is a quote-within-a-quote — "and here is such a 'quotation' as an example." For long quotes, you may wish to use Quotation templates.

When adding material to the biography of a living person

Main page: Wikipedia:Biographies of living persons

Biographies of living persons should be sourced with particular care, for legal and ethical reasons. All contentious material about living persons must cite a reliable source. If you find unsourced or poorly sourced contentious material about a living person — whether in an article or on a talk page — remove it immediately! Do not leave it in the article while you request a source. Do not move it to the talk page. This applies whether the material is in a biography or any other article.

When checking content added by others

You can also add sources for material you did not write. Adding citations is an excellent way to contribute to Wikipedia. See Wikipedia:WikiProject Fact and Reference Check for organized efforts to add citations.

When uploading an image

Images must include source details and a copyright tag on the image description page. It is important that you list the author of the image if known (especially if different from the source), which is important both for copyright and for informational purposes. Some copyright licenses require that the original author receive credit for their work. If you download an image from the web, you should give the URL:

Source: Downloaded from http://news.bbc.co.uk/1/hi/world/europe/4280841.stm

If you got the image from an offline source, you should specify:

Source: Scanned from public record #5253 on file with Anytown, Somestate public surveyor

Any image with a non-free copyright license must be accompanied by a non-free use rationale (also called a fair use rationale) for each article in which the image is used.

Putting together the citation

This section describes how to put together the text of a citation. Before you add it to a Wikipedia article, you may need to enclose it in tags or add an additional shortened version to the article. See "Adding the citation" for details.

Citation styles

Further information: Citation, APA style, MLA style, The Chicago Manual of Style, Author-date referencing, Vancouver system, Bluebook, and Wikipedia:Citing sources/example style

All citation techniques require detailed full citations to be provided for each source used. Full citations must contain enough information for other editors to identify the specific published work you used. There are a number of styles used in different fields. They all include the same information but vary in punctuation and the order of the author's name, publication date, title, and page numbers. Any of these styles is acceptable on Wikipedia so long as articles are internally consistent. You should follow the style already established in an article, if it has one. Where there is disagreement, the style used by the first editor to use one should be respected. There are some specific examples of citations here.

Full citations for books typically include:

• the name of the author or authors
• the title of the book
• the date of publication, and page numbers.
• The name of the publisher, city of publication, and ISBN are optional, although publisher is generally required for featured articles.

Full citations for journal articles typically include:

• the name of the author or authors
• year and sometimes month of publication
• the title of the article
• the name of the journal
• volume number, issue number (if the journal uses them), and page numbers

Citations for newspaper articles typically include:

• the title of the article in quotes,
• the byline (author's name),
• the name of the newspaper in italics,
• date of publication,
• page number(s)
• and a comment with the date you retrieved it if it is online (invisible to the reader).

Including page numbers

If you are quoting from, paraphrasing, or referring to a specific passage of a book or article, you should if possible also cite the page number(s) of that passage. In the case of books, the edition of the book should also be included because pagination can change between editions. Page numbers are especially important in case of lengthy unindexed books. Page numbers within a book or article are not required when a citation is for a general description of a book or article, or when a book or article, as a whole, is being used to exemplify a particular point of view.

Cite the place where you found the material

It is improper to obtain a citation from an intermediate source without making clear that you saw only that intermediate source. For example, you might find some information on a Web page that is attributed to a certain book. Unless you look at the book yourself to check that the information is there, your reference is really the Web page, which is what you must cite. The credibility of your article rests on the credibility of the Web page, as well as the book, and your article must make that clear.

Including external links

A citation ideally includes an external link to a source, or to information about the source.

If you have a URL (webpage) link, you can add it to the title part of the citation, so that when you add the citation to Wikipedia the URL becomes hidden and the title becomes clickable. To do this, enclose the URL and the title in square brackets—the URL first, then a space, then the title. For example:

Brown, R.: [http://webpage.html "Size of the Moon"], ''Scientific American'', 51(78):46.

For web-only sources you should also include a "Retrieved on" date in case the webpage changes in future: Retrieved on [[2008-07-15]].

You can also add an ID number to the end of a citation. The ID number might be an ISBN number for a book, a DOI (Digital Object Identifier) for an article, or any of several ID numbers that are specific to particular article databases, such as a PMID number for articles on Pubmed. It may be possible to format these so that they are automatically activated and become clickable when added to Wikipedia, for example by typing ISBN (or PMID) following by a space followed by the ID number.

If your source is not findable online, it should be findable in reputable libraries, archives, or collections. If a citation without an external link is challenged as unfindable, any of the following is sufficient to show the material to be reasonably findable (though not necessarily reliable): providing an ISBN or OCLC number; linking to an established Wikipedia article about the source (the work, its author, or its publisher); or directly quoting the material on the talk page, briefly and in context.

Convenience links

Further information: Wikipedia:Copyrights § Linking to copyrighted works

A "convenience link" is a link to a copy of your source on a webpage provided by someone other than the original publisher or author. For example, a copy of a newspaper article no longer available on the newspaper's website may be hosted elsewhere. When offering convenience links, it is important to be reasonably certain that the convenience copy is a true copy of the original, without any changes or inappropriate commentary, and that it does not infringe the original publisher's copyright. Accuracy can be assumed when the hosting website appears reliable, but editors should always exercise caution, and ideally find and verify multiple copies of the material for contentious items.

Where several sites host a copy of the material, the site selected as the convenience link should be the one whose general content appears most in line with Wikipedia:Neutral point of view and Wikipedia:Verifiability.

Sources in different languages

Because this is the English Wikipedia, English-language sources should be given whenever possible, and should always be used in preference to other language sources of equal caliber. However, do give references in other languages where appropriate. If quoting from a different language source, an English translation should be given with the original-language quote beside it. See also: Wikipedia:Verifiability#Non-English sources.

Citation templates and tools

Further information: Wikipedia:Citation templates

Citation templates are used to format citations in a consistent way. There are different sorts, which may be tailored to a particular kind of source (e.g. book, article). Their use is optional. Sometimes a particular template style will have become established for all the citations in a given article (you might notice this in edit mode) and it is advisable to try and use the same kind of template if possible. Because templates can be contentious, editors should not change an article with a distinctive citation format to another without gaining consensus.

There are several webpages/tools that can help quickly produce a citation in a standard template format. You may only need one piece of information and they can fill in the rest of the details. The resulting citation will be enclosed in "cite" tags, and it will be formatted in a particular way depending on which kind of template is being used. You can then copy all the text from there. It may still require additional tags before you can add it to a Wikipedia article.

There is a list of citation creation tools at the end of this article.

Technical details

There are (at least) two families of citation templates. The {{Citation}} template is intended to provide citations for many types of references. The other family has names of the form {{Cite xxx}} (for example, {{Cite book}} and {{Cite web}}). These two families produce different citation styles. For example, the {{Cite xxx}} family separates elements with a full stop, and gives page ranges as plain numbers, while the {{Citation}} template separates elements with a comma, and precedes page ranges with "pp." Thus, these two families should not be mixed in the same article.

The following construct using the {{Citation}} template produces a citation similar to the hand-formatted example citation in the Author-date referencing:How to write them subsection above:

* {{Citation |last=Ritter |first=R. |year=2002 |title=The Oxford Style Manual |publisher=Oxford University Press |isbn=0-19-860564-1}}

The {{Harv}} family of templates is available to produce author-date references in various formats with links matching the anchors produced by the {{Citation}} template. The following example constructs would produce references with different formatting styles having links matching the anchor produced by the example above:

Construct	Result
{{harv|Ritter|2002}}	(Ritter 2002)
{{harv|Ritter|2002|p=10}}	(Ritter 2002, p. 10)
{{harv|Ritter|2002|pp=5–10}}	(Ritter 2002, pp. 5–10)
{{harvtxt|Ritter|2002|pp=5–10}}	Ritter (2002, pp. 5–10)
{{harvnb|Ritter|2002|pp=5–10}}	Ritter 2002, pp. 5–10
{{harvcol|Ritter|2002|pp=5–10}}	(Ritter 2002:5–10)
{{harvcolnb|Ritter|2002|pp=5–10}}	Ritter 2002:5–10
<ref>{{harvcolnb|Ritter|2002|pp=5–10}}</ref>	places Ritter 2002:5–10 in a numbered footnote

It is possible to construct more exotic reference formats as well as to produce links with {{Harv}} family templates which match anchors produced by {{Cite xxx}} family templates (or any arbitrary anchor). The details are beyond the scope of this subsection, and can be found in the documentation of the individual templates.

Adding the citation

See also: Wikipedia:Referencing for beginners and Wikipedia:Verification methods

The way to add a citation on Wikipedia depends on which article you are contributing to and what exactly you are using the source for.

If a source supports a significant amount of the material in an article, it may sometimes be acceptable to simply add the citation at the end. It serves as a general reference, not linked to any particular part of the article. This is more likely to be appropriate for relatively undeveloped articles or those covering a very simple or narrow topic.

In most cases, an inline citation is required in addition to the full citation. This shows which specific part of the article a citation is being applied to. Inline citations are mandated by Wikipedia's featured article criteria and (to a lesser extent) the good article criteria. They are particularly appropriate for supporting statements of fact and are needed for statements that are challenged or likely to be challenged, including contentious material about living persons, and for all quotations.

The following are methods of inline citation used in Wikipedia:

Footnote system

Further information: Wikipedia:Footnotes

See also: Help:Footnotes

Many Wikipedia articles, particularly the more developed articles and those which meet good or featured article criteria, use a system of citation known as footnotes. Using this method results in clickable numbers within the text (the inline citation) that automatically link to a list of full citation at the end of the article.

If a footnotes system is being used in an article, and you edit the section at the end of the article that includes the list of citations, it will appear virtually empty. This is because you don't add the full citation there, but within the article text just after the point it is supporting. When you save your edit, Wikipedia software automatically turns the citation into a clickable number within the text, linked to an automatically generated list of full citations at the end of the article.

Before adding the citation, it needs to be enclosed in tags. Most commonly these are "ref" tags. You can add these by simply typing <ref> at the front of the citation and </ref> at the end. Alternatively you may notice below the edit box there is a list of "markup" which includes <ref></ref> - if you highlight your whole citation and then click this markup, it will automatically enclose your citation in ref tags.

If you now preview your edit, you may see a number in the text where you added the citation, or spot an error in how you formatted it. However, you may not be able to see the full citation listed even if you have done it correctly. Once you save your edit you will be able to follow the clickable number to the citation that should now be listed at the end of the article.

The example below shows what this would look like in the edit box:

The Sun is pretty big,<ref>Miller, E: "The Sun", page 23. Academic Press, 2005.</ref>
but the Moon is not so big.<ref>Brown, R: "Size of the Moon", ''Scientific American'', 51(78):46</ref>
The Sun is also quite hot.<ref>Miller, E: "The Sun", page 34. Academic Press, 2005.</ref>
==Notes==
<references/>

Below is how this would look in the article, once you had saved your edit:

The Sun is pretty big, but the Moon is not so big. The Sun is also quite hot.

Notes

---

Placement and punctuation

Material may be referenced mid-sentence or at the end of a sentence or paragraph. When a reference tag coincides with punctuation, the reference tag is normally placed immediately after any punctuation, except for dashes, as recommended by the Chicago Manual of Style and other style guides. Some editors prefer the in-house style of journals such as Nature, which place references before punctuation. If an article has evolved using predominantly one style of ref tag placement, the whole article should conform to that style unless there is a consensus to change it.

Using the same citation again

If you want to use the same citation to support another point in the same article, you do not need to add the whole citation again. In fact this would add unnecessary clutter in edit mode. Instead you can give the first citation a name. Then you only need to use that name in future in that article, instead of the whole citation.

The name you want to use goes inside the first ref tag. So instead of just <ref> it will say, for example: <ref name="Miller">. The tag at the end is the same, so in this example the whole thing would look like: <ref name="Miller2005">Miller, E: "The Sun", page 23. Academic Press, 2005</ref>.

From now on, at the point where you want to use the citation again, you just add: <ref name="Miller2005"/> In other words, it is the same as the ref tag used to give the first citation a name, but with an added / symbol. And you don't add anything else. If you forget the /, it will blank the rest of the article, so preview your change first.

Making an article use the footnotes system

If you are creating a new article or editing one that doesn't have automated citation listing (the footnotes or "ref tag" system), you can easily create this by making a new section towards the end of the article (usually headed "References") and adding one of these tags to it: <references/>, {{reflist}}, {{reflist|2}} or {{reflist|3}} (the last two are used to split long listings into columns). Three-column lists are inaccessible to users with smaller/laptop monitors and should be avoided. You may notice that two of these are included in the "markup" below the edit box; if you click on this it will add it to the page. Once you save your edit, inline citations enclosed in ref tags will be automatically generated in the new references section.

Shortened footnotes

Because the <ref> tag system works by including citations within the article text, it necessarily breaks up the text to some degree when in edit mode. In addition, if someone uses different page numbers from a source to support different points in the article, a separate full citation is created several times over. As a result, article text and citation lists can be difficult to read and maintain. In addition, the citation list will be in the same order as the citations appear in the text of the article, rather than ordered alphabetically for example.

As a result of these considerations, a slightly different use of the ref tags is sometimes made. In this system, you only add a shortened version of the full citation within the article text. It is still enclosed in ref tags, but just gives the author, year or title, and the page numbers. The list of these is still automatically generated in a section at the end of the article. Because these citations are shorter than full citations, they are called "shortened notes." The section in which they are listed is most commonly headed "Notes".

An extra "References" section should also still be created, where the full citations are manually added. They can be ordered alphabetically or by year, as is common in scientific articles. This serves as a reference list for full details on the source. A wikilink may be added between the short citation in the "Notes" section, and the full citation in the "References" section, allowing the reader to click on the shortened note and easily navigate to its appropriate full reference. See the "Further considerations (Wikilinks to full references)" for more details. Although each full citation needs to be added manually to this list, it forms one coherent block of code rather than being strewn throughout the text, so picking a specific source for further editing (e.g. adding ISBN, DOI or other detail) may be more convenient.

See the "Example edits for different methods" page for some examples comparing the use of shortened inline citations with the use of full inline citations.

Below is an edit mode view of adding "shortened notes" citations to an article:

The Sun is pretty big,<ref>Miller 2005, p.23.</ref>
but the Moon is not so big.<ref>Brown 2006, p.46.</ref>
The Sun is also quite hot.<ref>Miller 2005, p.34.</ref>
== Notes ==
{{reflist|2}}
== References ==
*Brown, R (2006). "Size of the Moon", Scientific American, 51(78).
*Miller, E (2005). "The Sun", Academic Press.

Below is how this would look one the edit was saved:

The Sun is pretty big, but the Moon is not so big. The Sun is also quite hot.

Notes

---

References

---

• Brown, R (2006). "Size of the Moon", Scientific American, 51(78).
• Miller, E (2005). "The Sun", Academic Press.

Shortened notes using titles rather than publication dates could look like this in the article:

Annotations via the footnote system

Further information: Wikipedia:Footnotes

The above footnote system is sometimes also used for annotations relating to points in the main text, for example quotations or comments that might be helpful to later fact-checkers. These may be kept in a section on their own, or be merged into the same section where citations are listed. See Wikipedia:Layout for further information on the placement and naming of these sections.

Parenthetical referencing

Further information: Wikipedia:Parenthetical referencing

A form of parenthetical referencing called author-date referencing is also used on Wikipedia. The inline citation in this method is a shortened version of the full citation and is visible within the text of the article in parentheses (round brackets like these). This method does not use the automated ref tag system or citation numbering, and is not referred to as footnotes. It requires both inline and full citations to be separately and manually added.

According to The Oxford Style Manual, author-date referencing is the most commonly used inline citation method in the physical and social sciences (Ritter 2002). It can be especially useful when a single, large work has to be referenced by page number multiple times, because each separate inline citation does not require an additional full citation at the end.

Under the this system, a short version of the citation is added in parentheses just after the point it is supporting. This short version comprises only the surname of the author(s) and the year of publication, and possibly page numbers. Page numbers must be included in a citation that accompanies a specific quotation from, or a paraphrase or reference to, a specific passage of a book or article. The inline citation usually looks like: (Author 2006:28) or (Author 2006, p.28).

The full citation is then added at the end of the article to a "References" section. This list of full citations is usually ordered alphabetically by author name.

Common rules for the inline citations in this system include:

• The parentheses close before the period marking the end of the sentence, as in the fake example at the end of this sentence (Jones 2005).
• You may name the author within the article itself, in which case only put the year in parentheses; for example "Smith (2005) says..."
• For two authors, use (Smith & Jones 2005); for three or more authors, use (Smith et al. 2005).
• If the same author has published two books in 1996, and both are being referenced in the text, this is written as (Clancy 1996a) and (Clancy 1996b).
• If the date of publication is unavailable, use "n.d." (meaning, no date)
• Newspaper articles may use the name of the newspaper and the date of publication after the sentence (The Guardian, December 17, 2005).
• A book published long after the original publication may be cited (Marx [1867] 1967).
• For a quotation that is within the text and marked by quotation marks, the citation follows the end-quotation mark ("), and is placed before the period (.), "like this" (Smith 2005).
• For a quotation that is indented, the citation is placed after the period, like the following. (Smith 2005)
• In cases where the author is unknown:

If the article is written for an organization or periodical then use its name, as in (Department of Transport 2001) or (National Geographic 2005),

otherwise, use the article title, italicized, as in (Advertising in the Western Cape 1990:14).

In the "References" section at the end of the article:

For a book: in the case of (Author 2005a) and (Author 2005b), this might be:

• Author, A. (2005a). Harvard Referencing, New York: Random House. ISBN 1-899235-74-4
• Author, A. (2005b). More Harvard Referencing, New York: Random House. ISBN 1-899235-74-4

For an article: in the case of (Traynor 2005) or (The Guardian, December 17, 2005), this might be:

• Traynor, I. "Judge tells Ankara to decide on fate of leading author", The Guardian, December 17, 2005.

Anchors

Creating a clickable link within the inline citation, which links to the full citation, is recommended. This is called an "anchor". An example is: (Ritter 2002). To cite Ritter one would first create an anchor to Ritter's work in the References section:

*<cite id=Ritter2002>Ritter, R. (2002). ''The Oxford Style Manual''. Oxford University Press. ISBN 0-19-860564-1</cite>

Then one would link to the anchor: [[#Ritter2002|Ritter 2002]] throughout the text, if necessary providing a page number.

Otherwise, you may use a citation template to anchor author-date references.

Further information: [[:Wikipedia:Citing sources/Example edits for different methods]]

Embedded links

Further information: Wikipedia:Embedded citations

If a webpage is used as a source, it can be linked to directly within the article by enclosing the URL in square brackets just after the point it is supporting. When the edit is saved, only a number is visible within the text. For example, a reference to a newspaper article can be embedded by adding: [http://media.guardian.co.uk/site/story/0,14173,1601858,00.html], which looks like this in the article: [1]

A full citation is also required in a References section at the end of the article. In addition, providing an access date for the link in a comment helps editors recover a link that has become unavailable. for example:

*Plunkett, John. [http://media.guardian.co.uk/site/story/0,14173,1601858,00.html "Sorrell accuses Murdoch of panic buying"], ''The Guardian'', [[October 27]], [[2005]]. <!--accessed June 5, 2008-->

which appears as:

• Plunkett, John. "Sorrell accuses Murdoch of panic buying", The Guardian, October 27, 2005.

Because of the difficulties in associating them with their appropriate full references, the use of embedded links for inline citations is not particularly recommended as a method of best practice and is not found in featured articles.

Need to qualify sources

Sources for uncontentious statements do not necessarily need to be described beyond adding the citation. No further description would be needed with the following, for example:

The word caffeine comes from the French term for coffee: café.

However, points which are more controversial, where there are contradictory studies or different opinions, may need to include more descriptive context to "qualify" the nature of the source. For example (from Super-recursive algorithm):

Martin Davis has described some of Burgin's claims as "misleading".

Here it is important to identify in the text exactly who is making the claim, since it would be inappropriate for Wikipedia to advocate that "Burgin's claims are misleading."

Further reading/External links sections

An ==External links== or ==Further reading== section is placed near the end of an article and offers books, articles, and links to websites related to the topic that might be of interest to the reader. The section "Further reading" may include both online material and material not available online. If all recommended material is online, the section may be titled "External links".

All items used as sources in the article must be listed in the "References" or "Notes" section, and are usually not included in "Further reading" or "External links". However, if an item used as a reference covers the topic beyond the scope of the article, and has significant usefulness beyond verification of the article, you may want to include it here as well. This also makes it easier for users to identify all the major recommended resources on a topic. The Wikipedia guideline for external links that are not used as sources can be found in Wikipedia:External links.

Scrolling lists

Scrolling lists, for example of references, should never be used because of issues with readability, accessibility, printing, and site mirroring. Additionally, it cannot be guaranteed that such lists will display properly in all web browsers.

Dealing with citation problems

Unsourced material

Main page: WP:PROVEIT

If an article has no references, and you are unable to find them yourself, you can tag the article with the template {{Unreferenced}}, so long as the article is not nonsensical or a WP:BLP, in which case request admin assistance. If a particular claim in an article lacks citation and is doubtful, consider placing {{fact}} after the sentence or removing it. Consider the following in deciding which action to take:

1. If a claim is doubtful but not harmful to the whole article or to Wikipedia, use the {{fact}} tag, but remember to go back and remove the claim if no source is produced within a reasonable time.

2. If a claim is doubtful and harmful, you should remove it from the article; you may want to move it to the talk page and ask for a source, unless you regard it as very harmful or absurd, in which case it should not be posted to a talk page either. Use your common sense. All unsourced and poorly sourced contentious material about living persons should be removed from articles and talk pages immediately. It should not be tagged. See Wikipedia:Biographies of living persons and Wikipedia:Libel.

What to do when a reference link "goes dead"

When a link "goes dead" (see link rot and Wikipedia:Dead external links), it should be repaired or replaced, if possible. In most cases, one of the following approaches will give an acceptable alternative.

• First, check the link to confirm that it is dead. The site may have been temporarily down or changed its linking structure. If the link has returned to service but has been labeled as a dead link, simply remove the labeling. See Template:dead link.
• Find a copy of the referenced document. There may be a copy of the referenced document in a web archiving service. If so, update the dead link to point to the copy of the referenced document.
  • For the Internet Archive, go to http://www.webarchive.org/. Also, see Wikipedia:Using the Wayback Machine. Note that there may be a delay of six months before a recent link shows up in the Internet Archive.
  • For WebCite, go to http://www.webcitation.org, and use their search page.
• Find a substitute for the referenced document. Enter key words or phrases or other content from the cited material into the referenced website's search engine, into a similar website's search engine, or into a general search engine such as Google. (A search engine may hold a cached version of the dead link for a short time, which can help find a substitute.) Or, browse the referenced document's website or similar websites. If you find a new document that can serve as a substitute, update the dead link to refer to the new document.
• Deactivate the dead link, and keep the citation information if still appropriate to the article. (This may happen, for example, when an online copy of material that originally appeared in print is no longer online.) In the remaining citation, note that the dead link was found to be inactive on today's date. Even with an inactive link, the citation still records a source that was used, and provides a context for understanding archiving delays or for taking other actions. In order to deactivate the dead link, do one of the following.
  • Turn the dead link into plain text. Remove only enough of the dead link's wikitext or markup language or URI scheme (square brackets, "http://", and so on) so that clicking on the link does not take you to its destination. This will make the link visible to both readers and editors of the article.
  • Turn the dead link into an HTML comment. Place HTML comment markup language around the link. This will make the link disappear when reading the article, but will preserve the link for editors of the article.

If a dead link cannot be repaired or replaced, consider reworking the article section so that it no longer relies on the dead link.

Whether a dead link can or cannot be repaired or replaced, remember that Wikipedia policy (including policy on sources and biographies of living persons) still applies. Consider doing further edits of the citation and cited material, if appropriate, to improve the article.

To help prevent dead links, consider citing reference sources using a persistent identifier such as a digital object identifier, if available; or consider archiving the referenced document online when writing the article section, if permitted by copyright. Also, consider avoiding links to web pages that usually disappear after short periods of time, such as at some news sites.

Tools

Citation creation tools

The following tools can help put together a full citation.

Web-based template fillers

These are tools with a website interface that provide a complete formatted reference based on a few initial details.

• Universal Reference Formatter

(Requires at least part of the citation text, or a URL link, or any one of several article ID numbers: ISBN, DOI, PMID, PMC, SICI)

• Google Scholar search add-on or here

(Search Google Scholar via this webpage and if you find a source you can click to autofill its details back into the Universal Reference Formatter)

• Reference Generator

(Depending on type of source, requires at least some part of citation, or a URL link, or some form of reference ID number)

• Diberri Template builder

(Requires a URL link or any one of several article ID numbers: DrugBank ID, HGNC ID, ISBN, PubMed ID, PubMed Central ID, PubChem ID)

• {{Cite book}} generator

(For books only; requires ISBN number)

Browser Add-ons

These tools can be integrated into your internet browser.

• WPCITE

(A Firefox add-in allowing you to create a partial {{cite news}} template. See the developer's page for details.)

• refToolbar

(A Javascript gadget, allowing you to format a reference during editing when you already have all the data.)

• Zotero

(A Mozilla Firefox add-on, Zotero allows you to find articles and easily paste their citations into Wikipedia as citation templates, using (on Windows) Ctrl-Alt-C or right-clicking the article and selecting "Export Selected Item..." then "Wikipedia Citation Templates.")

Article checkers

These tools can help you complete partial citations that are already in an article.

• DOI Bot

(Partial citations must either contain a DOI, or enough fields to be uniquely found.)

Misc

• WebCite

(WebCite archives a copy of an online source, so a citation can link to the archived copy as well as to the original URL (in case the latter changes in future).

• OttoBib

(OttoBib generates an alphabetized bibliography of books from a list of International Standard Book Number (ISBN) numbers, with output in MLA, APA, Chicago/Turabian, BibTeX, or Wikipedia format (also generates a permalink).

Citation processing tools

• User:CitationTool - tool for finding article-level citation errors and fixing them.
• DOI bot - automatically fixes common errors in individual citations, and adds missing fields

Programming tools

• Wikicite is a free program that helps editors to properly reference their Wikipedia contributions using citation templates. It is written in Visual Basic .NET, making it suitable only for users with the .NET Framework installed on Windows, or, for other platforms, the Mono alternative framework. Wikicite and its source code is freely available, see the developer's page for further details.
  • Wikicite+ is a program based on the original Wikicite source code. It features extra validation, bug fixes, additional cite templates (such as cite episode) as well as tools for stub sorting and more. It is also available for free under the Apache License 2.0 and will be open source in the future.
• pubmed2wiki.xsl a XSL stylesheet transforming the XML output of pubmed to Wikipedia refs.
• User:Richiez has tools to automatically handle citations for a whole article at a time. Converts occurrences of {{pmid XXXX}} or {{isbn XXXX}} to properly formatted footnote or Harvard style references. Written in ruby and requires a working installation with basic libraries.

See also

• Wikipedia:Verification methods - listing examples of the most common ways that references are used in Wikipedia articles.
• Wikipedia:Citing sources/example style – listing examples of full references using APA and Harvard referencing techniques.
• Wikipedia:Citing sources/Example edits for different methods - showing comparative edit mode representations for different citation methods and techniques.
• Wikipedia:Citing sources/Further considerations - information of additional interest.
• Wikipedia:Citation templates – a full listing of various styles for citing all sorts of materials.
• Wikipedia:Copyright problems – in case of text that has been copied verbatim inappropriately.
• Wikipedia:Referencing for beginners – a simple practical guide to getting started.
• Wikipedia:Scientific citation guidelines – guidelines for dealing with scientific and mathematical articles.
• Wikipedia:WikiProject Citation cleanup - a group of people devoted to cleaning citations
• Reference management software
  • Comparison of reference management software

References

• Concordia Libraries (Concordia University). Citation and Style Guides. (This provides a list of common citation styles.)
• Citation Styles Handbook: APA
• Citation Styles Handbook: MLA
• APA Style.org
• Using American Psychological Association (APA) Format (Updated to 5th Edition)
• Citing Electronic Documentation (APA, Chicago, MLA)
• The Columbia Guide to Online Style
• Ritter, R. (2002). The Oxford Style Manual. Oxford University Press. ISBN 0-19-860564-1
• University of Chicago Press Staff. (2003). The Chicago Manual of Style, 15th edition. University Of Chicago Press. ISBN 0-226-10403-6

Further reading

• A writer's practical guide to MLA documentation
• AMA Citation Style
• Chicago/Turabian Documentation
• Template:PDFlink
• Guide to Citation Style Guides
• Uniform Requirements for Manuscripts Submitted to Biomedical Journals
• American Chemical Society reference style guidelines
• Citation Machine