Types of Sources

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

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.

Characteristics of Encyclopedias

Authors are:

scholars in the field, academics or researchers.

Sources are:

always cited with many references and/or footnotes.

Books are:

long and in-depth research

They are:

sometimes edited, with multiple authors, look for university presses for scholarly books.

Find Encyclopedias

Encyclopedias are available in print and now, many 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) . New York, NY: Nova Science Publishers, Inc.

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

Feminism. (2011). In Encyclopædia Britannica. Retrieved from http://www.britannica.com/EBchecked/topic/724633/feminism