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History 151: McCauley

Primary, Secondary, & Tertiary Sources: What's the Difference?

A PRIMARY SOURCE is an original object or document from a specific time or event under study. Primary sources include historical and legal documents, interviews, eyewitness accounts, results of experiments, survey data, observations, diaries, paintings, works of literature, ancient pieces of pottery unearthed in Iraq, and much more. In the natural and social sciences, primary sources are often empirical studies — research where an experiment was done or a direct observation was made.

A SECONDARY SOURCE is anything that’s written about a primary source, such as an essay about a novel, a newspaper article about AIDS research, a movie review, or subsequent thoughts on The Gettysburg Address.

A TERTIARY SOURCE is a source that collects information from primary and/or secondary sources in one place, distilling, synthesizing or otherwise summarizing that information into a broad overview. Examples of tertiary sources are encyclopedias, Wikipedia, and textbooks.

Can a single source ever be more than one?

Occasionally, depending on context. For instance, if you are writing a paper about global warming, a newspaper article that discusses new research on the topic issue is a secondary source. But if you are writing a paper about the media’s coverage of global warming, then the newspaper article is a primary source. What you are studying changes your relationship to the material. To further muddy the water, a secondary source may very well include primary source materials in the form of pictures, statistics, or quotes, and that might work for your teacher, but it might not. Likewise, to ensure accuracy, it is a good practice to track down the primary source if you can just to verify it.

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