Some examples of tertiary sources are almanacs, guide books, survey articles, timelines, and user guides. Depending on the topic of research, a scholar may use a bibliography, dictionary, or encyclopedia as either a tertiary or a secondary source.
As tertiary sources, encyclopedias and textbooks attempt to summarize and consolidate the source materials into an overview, but may also present subjective commentary and analysis (which are characteristics of a secondary source).
See also 
- University of Maryland Libraries (2001) "Primary, Secondary and Tertiary Sources"
- Glossary, Using Information Resources
- Primary, Secondary & Tertiary Sources - James Cook University
- Primary, Secondary and Tertiary Sources, UM Libraries
- Søndergaard, T. F.; Andersen, J.; Hjørland, B. (2003). "Documents and the communication of scientific and scholarly information: Revising and updating the UNISIST model". Journal of Documentation 59 (3): 278. doi:10.1108/00220410310472509.