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Articles, Books, and . . . ? Understanding the Many Types of Information Found in Libraries

Content Type

What They Are

Use Them When You Need...

Reference Sources

Summaries of facts, definitions, histories, statistics, and other types of information on large subject areas, organized for quick lookup.

Examples: Encyclopedias, dictionaries, almanacs and yearbooks

  • Basic overviews of new subjects when you're getting started.
  • Quick lookup of factual info.
  • Referral to more detailed sources (like books and articles).


Long works providing in-depth analysis of a subject.

Examples: Novels, scholarly books, textbooks, dissertations

  • Comprehensive information that covers multiple techniques or sub-fields, long time spans, or multiple points of view.
  • Analysis of broad implications and "big picture" issues.


Short works providing news or analysis on narrowly-focused topics, published as part of some larger work.

Examples: Journal articles, magazine articles, newspaper articles

  • Narrowly focused analysis..
  • Detailed findings from individual studies.
  • The latest information on a topic.

Physical Media

You may notice that there's no page for e-books or online articles. That's because all of the content types here can be online. The categories here aren't about physical media, they're about the intellectual content contained in the pages or bytes. However, we've included notes about physical media.

In addition to print and online, other common media include:

  • microfilm, microfriche, and other microforms (ways of shrinking print down to tiny sizes)
  • CDs, DVDs, and other offline digital media
  • cassettesalbums, films, and other analog audo-visual media
  • realia, a catch-all term for artwork, cloth, toys, and other items that don't fit regular library categories

Scholarly Sources / Peer Reviewed

Professors often ask you to limit your research to scholarly sources. While there's no no hard and fast definition of "scholarly," it most commonly refers to peer-reviewed publications that adhere to academic writing standards such as citation of sources. Academic peer review is a process in which works are vetted by experts in the field before being accepted for publication.

It's not always obvious whether a specific book or journal is scholarly, and there are gray areas. Look for these signs:

  • Statement of peer-review policies in a journal's submission guidelines.
  • Published by a university press or reputable academic publisher.
  • Sources are cited, and the work includes a bibliography or list of references.

When in doubt, ask your professor or TA whether a specific source is acceptable.

Primary and Secondary Sources

Primary sources are "first-hand" information, sources as close as possible to the origin of the information or idea under study.

Secondary sources are works that provide summaries, analysis, commentary, or criticism on the primary source.

Precise definitions vary from field to field, and a single source can mix types. For example, a newspaper article written by a journalist is usually considered a secondary source, but any quotes from participants or eyewitnesses can be considered primary sources. Furthermore, definitions of "primacy" are relative; if that article contains the only remaining contemporary account of the event you're researching, it's as primary as you're going to get.