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How to Research Guide

DU Library

Primary, Secondary, & Tertiary

A primary source is an original document/image, the results of an experiment, statistical data, first-hand account, or creative work.  A secondary source is something written about or using primary sources.  A teritary source is a collection of primary and secondary sources.

Examples of Primary, Secondary, and Tertiary Sources

Primary Secondary Tertiary
The text of The Gettysburg Address An analysis of The Gettysburg Address A U.S. history textbook
Census data for Detroit A book about demographic changes in Detroit A chronology of major events in Detroit
A McDonald's commerical A documentary about McDonald's advertising An encyclopedia of major marketing campaigns
The results of an experiment or clinical trial An article citing different treatment options An medical dictionary
An interview with a World War Two veteran A documentary featuring interviews with veterans An anthology of first hand accounts from World War Two

Primary vs. Secondary