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Primary vs. Secondary Sources: Intro: Distinguishing Source Types

How to differentiate among primary, secondary, and tertiary sources in the research process, and tips on finding primary sources.


Often your professor will suggest that you use primary, secondary, or tertiary materials for your research project. It is not always easy to tell the difference between these resources, and what counts as a primary source differs between disciplines.

Use the charts to help you understand these distinctions.  Please consult your professor or a librarian if you are unsure about identifying a particular source.

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Primary Sources Quick Take

Area of Research Definition/Examples
Cultural or historical studies

Original records* that were either created at the time historical events occurred, or well after those events in the form of memoirs and oral histories.

*Records could be news articles, images, government reports, speeches, social media, interviews, etc.

Literary studies Original literary works, as well as letters, diaries, notes, and marginalia written by authors.
Scientific research

Articles reporting on the results of original research, as well as the data* gathered by scientists.

*Data could be measurements, images, audio, interviews, etc.

Primary vs. Secondary vs. Tertiary Sources

DEFINITION An original object or document: the raw research or first-hand information. Comments on, interpretations of, or discussions about the primary or original source. Provide background information or compilations by synthesizing information gathered from other sources, usually secondary sources.
TIMING Primary sources usually come first in the timing of scholarly publication. Secondary sources usually come second in the timing of scholarly publication. Tertiary sources usually come third or last in the timing of scholarly publication.
  • Letters & diaries
  • Speeches and interviews
  • First-hand news accounts
  • Government reports
  • Laws and legislation
  • Creative writings (ex. novels or poetry)
  • Results of scientific experiments
  • Critical reaction to an experiment or to a piece of literature
  • Analysis of social, cultural or economic trends
  • Review of the literature on a topic
  • Overviews or background info (ex. encyclopedias)
  • Compilation of citations an abstracts (ex. library databases)
  • Statistical handbooks
EXAMPLES    Politics Major
(studying terrorism in the wake of the 9/11 attacks)
National Commission on Terrorist Attacks upon the United States. (2004). The 9/11 Commission report: final report. New York: Norton. Carpenter, T. (2005, Winter). Missed Opportunities: The 9/11 Commission Report and US Foreign Policy. Mediterranean Quarterly, 16(1), 52–61.
  • Worldwide Political Science Abstracts (Library database)
  • Encyclopedia of terrorism and political violence
EXAMPLES    English Major
(studying creative writings about terrorism)
Updike, J. (2006). Terrorist (a novel). New York: Alfred A. Knopf. Steyn, M. (2006, July 31). Why John Updike's book is a bomb. Maclean's, 119 (29), 58–59.
  • Literature Resource Center (Library database)
  • Miller, R. (1988). The literature of terrorism. Terrorism 11 (1), 63-87.
EXAMPLES  Psychology Major
(studying the psychological effects of the 9/11 Attacks on children)
Schuster, M. A., B. D."A National Survey of Stress Reactions After the September 11, 2001 Terrorist Attacks," New England Journal of Medicine, Vol. 345, No. 20, November 15, 2001, pp. 1507–1512. Alexander, G. (2007). International relations theory meets world politics. In Understanding the Bush Doctrine: Psychology and strategy in an age of terrorism (pp. 39–64). New York, NY, US: Routledge/Taylor & Francis Group.
  • PsycINFO (Library database)
  • Kazdin, A. E. (2000). Encyclopedia of psychology. Washington, D.C.: American Psychological Association.
Biology Major
(studying bioterrorism)
United States. (2003). Project Bioshield Act of 2003 report (to accompany H.R. 2122). Washington, D.C.: U.S. G.P.O. Alexander, D., & Klein, S. (2003, December). Biochemical terrorism: too awful to contemplate, too serious to ignore: subjective literature review. British Journal of Psychiatry, 183 (6), 491–497.
  • Biological Sciences (Library database)
  • Pilch, R. F., & Zilinskas, R. A. (2005). Encyclopedia of bioterrorism defense. Hoboken, N.J.: Wiley-LISS.


This chart was adapted from a research guide prepared by the Library at the University of North Carolina Wilmington.