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Types of Sources

So many choices! Use this guide to determine when to use a book, journal, video, encyclopedia or other sources.

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About Encyclopedias

Encyclopedias contain brief factual articles on many subjects. There are two types of encyclopedias -- general and subject.

  • General encyclopedias provide overviews on a wide variety of topics. 
  • Subject encyclopedias contain entries focusing on one field of study.

Use an encyclopedia:

  • when looking for brief background or overview information on a topic
  • when trying to find key ideas, important dates or concepts


Use wisely and with a bit of skepticism! Verify using other possibly more reliable sources. Professors at WPI generally don't want to see Wikipedia references in bibliographies. Wikipedia can be a useful starting point as you look for ideas of what you want to learn more about, but it is not a source that you will cite in your paper. Remember this rule: Wikipedia is a good place to start but not a good place to finish.

Characteristics of Encyclopedias

Authors are:

varied, some are scholars.

Sources are:

sometimes cited.

Entries are:

sometimes short, designed to give an overview of a subject

Find Encyclopedias

Many encyclopedias are available online.

How to Cite

Example hardcopy encyclopedia reference citation in American Psychological Association (APA)style:

Yang, G. W. (2009). Thermodynamic and kinetic theories of nanowire growth. In Encyclopedia of nanotechnology (Vol. 1, pp. 201-235). Nova Science Publishers.

 Example electronic encyclopedia reference citation in American Psychological Association (APA) style:

Brunell, L. (2020). Feminism. In Encyclopædia Britannica

For information on additional citation styles, please see the Citing Sources guide.