Tertiary literature

Learning objectives

At the end of this module, you will be able to:

  • determine the value of different tertiary sources for your research.
  • critically assess the accuracy of online reference works.
  • find review articles using Google Scholar.

What are tertiary sources?

These are sources that summarise, abstract or index the information derived from primary or secondary sources. These sources can assist you to find background information on your topic (such as definitions, names and dates) or take you to relevant books and general articles. Examples of tertiary sources include:

  • encyclopedias.
  • dictionaries.
  • atlases.
  • handbooks.
  • indexes.
  • review articles.

Note that not all reference works are equally authoritative. Some are surprisingly poor, containing obvious errors. It is important to cross-check what you read in a reference work against other sources.

Free reference works on the Web

There are also a range of free reference works on the Web. Most of these — such as countless versions of the 1911 Encyclopedia Britannica — are of little value and should be avoided.


Wikipedia is a free, Web-based encyclopedia which has been available since 2001. Wikipedia will often give you a quick answer when you require basic information. Despite this, Wikipedia needs to be treated with caution. Contributors range from well-informed to the eccentric. A particular strength of Wikipedia is that it contains articles relating to modern life and popular culture. Encyclopedia Britannica, for example, lacks articles on both the American politician Lyndon LaRouche and the fantasy author Robert E. Howard (the creator of Conan the Barbarian). In contrast, Wikipedia has exhaustive, well-referenced articles on both LaRouche and Howard.

Review articles

Review articles are a particularly useful form of a tertiary source. They provide an overview of the latest research that has been carried out in a particular area of study. Many review articles can be found in Annual Reviews. Others are published in regular academic journals.

One easy way to find review articles is to use Google Scholar. Enter your keywords, and then add the words review article in quotation marks.

For, example, to search for review articles on health insurance, search for:

"health insurance" ("review article" OR  "literature review")

Even such a simple search yields hundreds of results.


This module deals with the following topics:

  • identifying different types of tertiary sources.
  • finding printed reference works.
  • finding online reference works.
  • the need to assess the accuracy of online reference works.
  • finding review articles.

Web research