|This essay contains the advice or opinions of one or more Wikipedia contributors on the Verifiable policies and the Citing Sources guidelines. Essays are not Wikipedia policies or guidelines. Some essays represent widespread norms; others only represent minority viewpoints.|
|This page in a nutshell: When citing material in an article, it is better to cite a couple of great sources than a stack of decent or sub-par sources.|
Wikipedia requires material to be verifiable. This means adding some form of inline citations for anything challenged or likely to be challenged, and for all direct quotations. While adding footnotes is helpful, adding too many can cause citation clutter, which can make articles look untidy in read mode, and unreadable in edit mode. If a page has extra citations that are either mirror pages or just parrot the other sources, they contribute nothing to its reliability while acting as a detriment to its readability.
One cause of "citation overkill" is edit warring, which can lead to examples such as "Garphism is the study of ...". Extreme cases have seen fifteen or more footnotes after a single word, as an editor desperately tries to shore up his or her point and/or overall notability of the subject with extra citations, in the hope that his or her opponents will accept that there are reliable sources for his/her edit.
The purpose of any article is first and foremost to be read – unreadable articles do not give our readers any material worth verifying. It is also important for an article to be verifiable. Without citations, we cannot know that the material isn't just made up unless it is a common sense case (see WP:BLUE). A good rule of thumb is that, except for certain controversial topics, one footnote after a sentence is almost always sufficient. Two or three may be a good way of preventing linkrot for online sources or providing a range of sources that support the fact, but more than three should usually be avoided; if more than three are truly beneficial as an additional range, consider WP:Bundling (merging) the citations.
Not only does citation overkill impact the readability of an article, it can call the notability of the subject into question by editors. A well-meaning editor may attempt to make a subject which does not meet Wikipedia's notability guidelines appear to be notable through quantity of sources. Ironically, this serves as a red flag to experienced editors that the article needs scrutiny and that each citation needs to be verified carefully to ensure that it was really used to contribute to the article.
Misuse to prove an obvious point
It is possible that an editor who is trying to promote an article to GA-class (good article status) might add citations to basic facts such as "...the sky is blue...". While this might be a good thing in their eyes, the fact that the sky is blue does not usually require a citation. In all cases, editors should use common sense.
Material that is repeated multiple times in an article does not require an inline citation for every single mention. If you have occasion to mention the fact that an elephant is a mammal in multiple places in an article, you would do well to provide a citation after the first one, but you need not follow each and every occurrence of the word mammal with another copy of the citation.
Avoid cluttering text with redundant citations like this:
Elephants are large land mammals ... Elephants' teeth are very different from those of most other mammals. Unlike most mammals, which grow baby teeth and then replace them with a permanent set of adult teeth, elephants have cycles of tooth rotation throughout their entire lives.
- 1. Expert, Alice. (2010) Size of elephants: large.
- 2. Smith, Bob. (2009) Land-based animals, Chapter 2: The Elephant.
- 3. Christenson, Chris. (2010) An exhausting list of mammals
- 4. Maizy, Daisy. (2009) All about the elephants' teeth, p. 23–29
In addition, as per WP:PAIC, citations should be placed at the end of the passage that they support. If one source alone supports consecutive sentences in the same paragraph, one citation of it at the end of the final sentence is sufficient. It is not necessary to include a citation for each individual consecutive sentence, as this is overkill. This does not apply to lists or tables, nor does it apply when multiple sources support different parts of a paragraph or passage.
This is correct:
In the first collected volume, Marder explains that his work is "about the affinity of life," wherein the characters "understand that ultimately they depend on each other for survival." Wiater and Bissette see in this relationship as a wider metaphor for the interdependancy of the comics industry. Indeed, addressing the potential underlying complexity, Marder suggests that "it's harder to describe it than it is to read it." He also calls it "an ecological romance... a self-contained fairy tale about a group of beings who live in the center of their perfect world [and are] obsessed with maintaining its food chain," a self-described "really low concept!" Equally, he says, "the reader has to invest a certain amount of mental energy to follow the book," which includes "maps and a rather long glossary." Despite these potentially conflicting comments, Wiater and Bissette reiterate that "there is no simpler or more iconographic comic book in existence."<ref name="Rebels">[[Stanley Wiater|Wiater, Stanley]] & [[Stephen R. Bissette|Bissette, Stephen R.]] (ed.s) "Larry Marder Building Bridges" in '''''Comic Book Rebels''': Conversations with the Creators of the New Comics'' (Donald I. Fine, Inc. 1993) ISBN 1-55611-355-2 pp. 17–27</ref>
This is also correct, but is overkill:
In the first collected volume, Marder explains that his work is "about the affinity of life," wherein the characters "understand that ultimately they depend on each other for survival."<ref name="Rebels">[[Stanley Wiater|Wiater, Stanley]] & [[Stephen R. Bissette|Bissette, Stephen R.]] (ed.s) "Larry Marder Building Bridges" in '''''Comic Book Rebels''': Conversations with the Creators of the New Comics'' (Donald I. Fine, Inc. 1993) ISBN 1-55611-355-2 pp. 17–27</ref> Wiater and Bissette see in this relationship as a wider metaphor for the interdependancy of the comics industry.<ref name="Rebels" /> Indeed, addressing the potential underlying complexity, Marder suggests that "it's harder to describe it than it is to read it."<ref name="Rebels" /> He also calls it "an ecological romance... a self-contained fairy tale about a group of beings who live in the center of their perfect world [and are] obsessed with maintaining its food chain," a self-described "really low concept!"<ref name="Rebels" /> Equally, he says, "the reader has to invest a certain amount of mental energy to follow the book," which includes "maps and a rather long glossary."<ref name="Rebels" /> Despite these potentially conflicting comments, Wiater and Bissette reiterate that "there is no simpler or more iconographic comic book in existence."<ref name="Rebels" />
One can additionally hide citations with
<!-- --> to prevent confusion in the future.
Another common form of citation overkill is to cite multiple reprintings of the same content in different publications — such as several different newspapers reprinting the same wire service article, or a newspaper or magazine article getting picked up by a news aggregator — as if they constituted distinct citations. Such duplicated citations may be piled up as multiple references for the same fact or they may be split up as distinct footnotes for different pieces of content, so watching out for this type of overkill may sometimes require special attention.
This type of overkill should be resolved by merging all of the citations into a single one and stripping unhelpful repetitions — when possible, the retained citation should be the originator of the content rather than a reprinter or aggregator, but if this is not possible (e.g. some wire service articles) then retain the most reliable and widely-distributed available reprinter (for example, if the same article has been linked to both The New York Times and The Palookaville Herald, then The New York Times should be retained as the citation link.)
How to trim excessive citations
If there are six citations on a point of information, and the first three are highly reputable sources (e.g., books published by university presses), and the last three citations are less reputable or less widely circulated (e.g., local newsletters), then trim out those less-reputable sources.
If all of the citations are to highly reputable sources, another way to trim their number is to make sure that there is a good mix of types of sources. For example, if the six citations include two books, two journal articles, and two encyclopedia articles, the citations could be trimmed down to one citation from each type of source. Comprehensive works on a topic often include many of the same points. Not all such works on a topic need be cited – choose the one or ones that seem to be the best combination of eminent, balanced, and current.
In some cases, such as articles related to technology or computing or other fields that are changing very rapidly, it may be desirable to have the sources be as up-to-date as possible. In these cases, a few of the older citations could be removed.
For many subjects, some sources are official or otherwise authoritative, while others are only interpretative, summarizing, or opinionated. If the authoritative sources are not controversial, they should generally be preferred. For example, a company's own website is probably authoritative for an uncontroversial fact like where its headquarters is located, so newspaper articles need not be cited on that point. The World Wide Web Consortium's specifications are, by definition, more authoritative about HTML and CSS than third-party Web development tutorials.
Try to construct passages so that an entire sentence or more can be cited to a particular source, instead of having sentences that each require multiple sources.
If there is a good reason to keep multiple citations, for example, to avoid perennial edit warring or because the sources offer a range of beneficial information, clutter may be avoided by merging the citations into a single footnote. This can be done by putting, inside the reference, bullet points before each source, as in this example, which produces all of the sources under a single footnote number. Within a simple text citation, semicolons can be used to separate multiple sources.
Each of these articles has been corrected. Links here are to previous versions where a citation problem existed.
- 2004 Madrid train bombings on
- – (No longer contains this issue)
- – 172 citations for one sentence (article was not in the mainspace at the time, no longer contains this issue)
- - 19 citations
- – 65 citations in opening paragraph (the article no longer contains this issue)
- – (No longer contains this issue)
- – 14 citations for one statement
- – Sixteen citations
- – 27 citations for the two variations of the article title
- 6 consecutive citations of the same source in one paragraph (Fixed)
- Wikipedia:Wisps' Law
- Wikipedia:You don't need to cite that the sky is blue
- Wikipedia:Masking the lack of notability
- Wikipedia:Overlink crisis
- mw:Extension:HarvardReferences – extension to improve references into Harvard style
- User:Piotrus/Wikipedia:Why most sentences should be cited
- Category:Citation overkill, for Wikipedia articles that display a case of citation overkill