Wikipedia:Identifying and using tertiary sources

Generally speaking, tertiary sources (for Wikipedia purposes, as discussed at WP:No original research § Primary, secondary and tertiary sources, and WP:Identifying reliable sources § Primary, secondary, and tertiary sources) include any compilation of information, without significant new analysis, commentary, or synthesis, from primary and secondary sources, especially when it does not indicate from which sources specific facts were drawn. The distinction is important, because WP:No original research policy states: "Articles may make an analytic or evaluative claim only if that has been published by a reliable secondary source." Thus, such claims cannot be cited to tertiary (or primary) sources.

There are many examples:

• Encyclopedias, compendia, and dictionaries (whether general or topical).
• "Coffee table books" and "bathroom books".
• School textbooks, especially below the graduate school level.
• Bibliographies and indexes, concordances, thesauri, databases, almanacs, travel guides, field guides, timelines, and similar works.
• Abstracts of academic journal articles prepared by indexing services (an abstract prepared by the author[s] of a paper is a primary source, like the paper itself).

Some of the above kinds of tertiary sources are considered forms of secondary literature in some disciplines, but remain tertiary for Wikipedia's purposes.

Exceptions

Tertiary → secondary: Sometimes high-quality, generally tertiary individual sources are also secondary sources for some material; two examples are etymological research that is the original work of a dictionary's staff; and analytical not just regurgitative material in a topical encyclopedia written by a subject-matter expert. Material found in university textbooks ranges from secondary to tertiary, even in the same work, but is most often tertiary, especially at lower levels and covering more basic subjects. Textbooks intended for children are tertiary.

Secondary → tertiary: Some material published in general news sources (which are usually secondary) is actually tertiary, such as topical overview articles that summarize publicly-available information without adding any investigation or analysis, and sidebars of unsourced statistics or other factoids. By contrast, academic review articles (i.e., literature reviews and systematic reviews) are secondary sources, especially when they are themselves peer-reviewed. (These are not to be confused with a review in the more general sense, which is a primary source representing the personal opinion of a reviewer of a film, book, etc.).

Tertiary → primary, and vice versa: Certain kinds of sources that are usually tertiary may in some instances be primary, e.g. rules published by a sport's governing body vs. found in a compendium of sports and games. Some usually primary types of sources, such as user guides and manuals, are tertiary (or even secondary, depending on their content) when written by parties independent of the subject, e.g. computer operating system guides found in bookstores. Primary source material that is simply reprinted in an otherwise tertiary (or secondary) source remains primary.

Tertiary online sources that are written in whole or in part by a general-public editing community are user-generated content, and are not reliable sources. This includes content farms, which have a paid but indiscriminate array of innumerable writers, and little editorial oversight.

Determining reliability

Main page: Wikipedia:Identifying reliable sources

Reliability of a tertiary source is principally determined by four factors: whether its producers (i.e. writers and/or editors) have subject-matter expertise, whether the underlying original sources of the non-novel material are clear, whether its producers are independent of the subject, and whether the work is generally regarded as reliable by others in the field in question. These factors counterbalance each other. For example, while typical mainstream dictionaries do not cite sources for specific entries, how authoritative they are considered can be gleaned from independent editorial reviews of their content and editorial practices.

See also

• WP:No original research (policy)
• WP:Verifiabilty (policy)
• WP:Identifying reliable sources (guideline)
• WP:Party and person (essay on the distinctions between terms like "tertiary" and "third party")
• WP:Independent sources (essay on how to identify when a source may be biased due to a connection to its subject)
• Template:Tertiary source inline (used outside <ref>...</ref>)
• Template:Tertiary source (used inside <ref>...</ref>)