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Identify Primary, Secondary, Tertiary Sources

Learn about primary, secondary, and tertiary sources.

What you'll find on this page

On this page, you'll learn:

  • what primary sources are and what they look like in different disciplines

  • where to find primary sources

  • how to use primary sources

  • additional tips to help you identify whether a source is primary

What are primary sources?

Primary sources are materials that you explain, analyze, or interpret, and which get you as close as possible to the idea, event, or topic you are researching without analysis of the topic. They are the ground-level evidence for that topic.

Primary sources often look different depending on your discipline. For example:

In STEM & medical fields In the humanities & social sciences
articles describing the research design and findings of original studies journals, diaries & letters
patents & blueprints historical newspapers
works of art & literature
reports on original research government documents
field research

Where to find primary sources

Remember: any source can be a primary source, depending on your research question/topic.

To find primary sources, you can:

  • Select the material type(s) you are looking for on the search results of many databases using filters
    material type selection in databases
  • Search for a material type (diary, speech, etc.) + your topic (World War II, bicycle, etc.) using the search box at, or the one below:


For subject-specific assistance in finding primary sources, visit:

How to use primary sources

When your professor asks you to use primary sources in your writing, you are being asked to quote, paraphrase, and incorporate them in the following ways:

Pro tips

1) A source which may be secondary or tertiary in another context (like an encyclopedia) could be used as a primary source, depending on the research topic. Take this book:

  • Writing a paper on Homer Simpson's origin story? Then this book is a tertiary source, because you'll use it to get background information.
  • Writing a paper about male-centrism in cartoon encyclopedias? Then this book is a primary source, because you'll analyze it as an example.

2) Primary sources can be scholarly/peer-reviewed… or not.

  • Scenario:  a student writing about civilian life during World War II uses a diary as a primary source. Diaries are not reviewed by other 'expert' diarists before publication, so they are not scholarly.
  • Scenario:  a student writing about debunked research uses an article published in a prestigious journal connecting autism to vaccines as a primary source. This journal peer-reviews all of its articles, so this source is scholarly (if incorrect in this case).
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