39 Primary, Secondary, and Tertiary Sources

Teaching & Learning, University Libraries and Christina Frasier

Learning Objectives

  • Identify  and differentiate between primary, secondary, and tertiary sources.
  • Recognize the trickiness of classifying primary and secondary sources according to how their material is used in a research project.

An information category is called publication mode and has to do with whether the information is:

  • A primary source, or firsthand information (information in its original form, not translated or published in another form).
  • A secondary source, or secondhand information (a restatement, analysis, or interpretation of original information).
  • A teritiary source, or third-hand information (a summary or repackaging of original information, often based on secondary information that has been published).

The three labels for information sources in this category are, respectively, primary sources, secondary sources, and tertiary sources. Here are examples to illustrate the first-handedness, second-handedness, and third-handedness of information:


  • Primary source (original, firsthand information): J. D. Salinger’s novel Catcher in the Rye
  • Secondary source (secondhand information): A book review of Catcher in the Rye
  • Tertiary source (third-hand information): Wikipedia page about J. D. Salinger

When you make distinctions between primary, secondary, and tertiary sources, you are relating the information itself to the context in which it was created. Understanding that relationship is an important skill that you’ll need in college, as well as in the workplace. Noting the relationship between creation and context helps us understand the “big picture” in which information operates and helps us figure out which information we can depend on. That’s a big part of thinking critically, a major benefit of actually becoming an educated person.

Primary Sources – Because it is in its original form, the information in primary sources has reached us from its creators without going through any filter. We get it firsthand. Here are some examples that are often used as primary sources:

  • Any literary work, including novels, plays, and poems
  • Diaries
  • Advertisements
  • Music and dance performances
  • Eyewitness accounts, including photographs and recorded interviews
  • Artworks
  • Data
  • Blog entries that are autobiographical
  • Scholarly blogs that provide data or are highly theoretical, even though they contain no autobiography
  • Artifacts such as tools, clothing, or other objects
  • Original documents such as tax returns, marriage licenses, and transcripts of trials
  • Buildings
  • Correspondence, including email
  • Records of organizations and government agencies
  • Journal articles that report research for the first time (at least the parts about the new research, plus their data)
  • Some social media posts–depending on your focus (see example below)

Secondary Source – These sources are translated, repackaged, restated, analyzed, or interpreted original information that is a primary source. Thus, the information comes to us secondhand, or through at least one filter. Here are some examples that are often used as secondary sources:

  • All nonfiction books and magazine articles except autobiography
  • An article or website that critiques a novel, play, painting, or piece of music
  • An article or web site that synthesizes expert opinion and several eyewitness accounts for a new understanding of an event
  • The literature review portion of a journal article

Tertiary Source – These sources further repackage the original information because they index, condense, or summarize the original.

Typically, by the time tertiary sources are developed, there have been many secondary sources prepared on their subjects, and you can think of tertiary sources as information that comes to us “third-hand.” Tertiary sources are usually publications that you are not intended to read from cover to cover but to dip in and out of for the information you need. You can think of them as a good place for background information to start your research but a bad place to end up. Here are some examples that are often used as tertiary sources:

  • Almanacs
  • Dictionaries
  • Handbooks, including the one you are now reading
  • Timelines
  • Bibliographies
  • Encyclopedias, including Wikipedia
  • Blog posts reposting news stories or articles
  • Online comments on social media posts (such as Reddit comments)

Tertiary sources are usually not acceptable as cited sources in college research projects because they are so far from firsthand information. That’s why most professors don’t want you to use Wikipedia as a citable source: the information in Wikipedia is far from original information. Other people have considered it, decided what they think about it, rearranged it, and summarized it–all of which is actually what your professors want you, not another author, to do with information in your research projects.

Which Kind of Source?

The details are tricky— A few things about primary or secondary sources might surprise you:

  • Sources become primary rather than always existing as primary sources.

It’s easy to think that it is the format of primary sources that makes them primary. But that’s not all that matters. So when you see lists like the one above of sources that are often used as primary sources, it’s wise to remember that the ones listed are not automatically already primary sources. Firsthand sources get that designation only when researchers actually find their information relevant and use it.


  • A diary about missions kept by an American helicopter pilot in the Vietnam War is not a primary source until a researcher uses it in her study of how the war was carried out. But it will never be a primary source for a researcher studying the U.S. public’s reaction to the war because it does not contain information relevant to that study.


  • Primary sources, even eyewitness accounts, are not necessarily accurate. Their accuracy has to be evaluated, just like that of all sources.
  • Something that is usually considered a secondary source can be considered a primary source, depending on the research project.


  • Movie reviews are usually considered secondary sources. But if your research project is about the effect movie reviews have on ticket sales, the movie reviews you study would become primary sources
  • Likewise, social media posts are usually secondary or tertiary sources unless you are writing specifically about one type of social media post.


Despite their trickiness, what primary sources usually offer is too good not to consider using because:

  • They are original. This unfiltered, firsthand information is not available anywhere else.
  • Their creator was a type of person unlike others in your research project, and you want to include that perspective.
  • Their creator was present at an event and shares an eyewitness account.
  • They are objects that existed at the particular time your project is studying.

Particularly in humanities courses, your professor may require you to use a certain number of primary sources for your project. In other courses, particularly in the sciences, you may be required to use only primary sources.

What are considered primary and secondary sources can vary from discipline to discipline. If you are required to use primary sources for your research project, before getting too deep into your project check with your professor to make sure he or she agrees with your choices. After all, it’s your professor who will be grading your project. A librarian, too, can verify your choices. Just remember to take a copy of your assignment with you when you ask, because the librarian will want to see the original assignment.

Adapted from English Composition: Connect, Collaborate, Communicate by Ann Inoshita; Karyl Garland; Kate Sims; Jeanne K. Tsutsui Keuma; and Tasha Williams, CC BY 4.0 


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Primary, Secondary, and Tertiary Sources Copyright © by Teaching & Learning, University Libraries and Christina Frasier is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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