2-Types of Sources

4. Primary, Secondary & Tertiary Sources

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Another way to categorize information is by whether the information is in its original format or has been reinterpreted.

Another way to categorize information is by whether the information is in its original format or has been reinterpreted.

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

  • Firsthand information—primary sources (information in its original form, not interpreted, translated, or published in another form).
  • Secondhand information—secondary sources (a restatement, analysis, or interpretation of original information).
  • Third-hand information—tertiary sources (a summary or repackaging of original information, often based on secondary information that has been published).

Here are examples to illustrate the first-handedness, second-handedness, and third-handedness of information:


Primary Source Secondary Source Tertiary Source
Original, Firsthand Information Secondhand Information Thirdhand Information
Example: J.D. Salinger’s novel Catcher in the Rye. A book review of Catcher in the Rye, even if the reviewer has a different opinion than anyone else has ever published about the book. They are still just reviewing the original work and all the information about the book here is secondary. 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, at least in disciplines other than the sciences:

  • Any literary work, including novels, plays, and poems.
  • Breaking news.
  • 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.
  • Websites, although many are secondary.
  • 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).

(The term primary source doesn’t come up much in the sciences. Scientists often call a journal article that was the most helpful to their work their primary source.)

Secondary Source – These sources are translated, repackaged, restated, analyzed, or interpreted information from 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 website 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 used in secondary sources as 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 “thirdhand.” 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
  • Guide books, including the one you are now reading
  • Survey articles
  • Timelines
  • Bibliographies
  • Encyclopedias, including Wikipedia
  • Most textbooks

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 students, not another author, to do with the information in your research projects.

Activity: Primary, Secondary, or Tertiary?


The Details Are Tricky— A few things about labeling primary or secondary sources might surprise you:

  • Sources become primary rather than always exist 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.

For instance: Records that could be relevant to those studying government are created every day by federal, state, county, and city governments as they operate. But until those raw data are actually used by a researcher, they cannot be considered primary sources.

Another example: A diary about flying missions kept by an American helicopter pilot in the Vietnam War is not a primary source until, say, 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. But if a researcher were to study, say, pilots’ long-term opinions about serving in the war and used that diary as a source, then it would become a primary source.

  • Primary sources, even eyewitness accounts, are not necessarily accurate. Their relevance and credibility have 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.

For instance, 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.

  • Deciding whether to consider a journal article a primary or a secondary source can be complicated for at least two reasons.

First, journal articles that report new research for the first time are usually based on data collected by the author or others. So some disciplines consider the data to be the primary source and consider the journal article that describes and analyzes them a secondary source.

However, particularly in the sciences, the original researcher might find it difficult or impossible (he or she might not be allowed) to share the data. So sometimes you have nothing more firsthand than the journal article, which argues for calling it the relevant primary source because it’s the closest thing that exists to the data.

Second, even journal articles that announce new research for the first time usually contain more than data. They also typically contain secondary source elements, such as a literature review, bibliography, and sections on data analysis and interpretation. So they can actually be a mix of primary and secondary elements. Even so, in some disciplines such as the sciences, a journal article that announces new research findings for the first time is considered to be, as a whole, a primary source for the researchers using it, particularly if it is where they got most of the information on which to base their own journal article.


ACTIVITY: Under What Circumstances?

Instructions: Look at each of the sources listed below and think of circumstances under which each could become a primary source. (There are probably many potential circumstances for each.) So just imagine you are a researcher with projects that would make each item firsthand information that is relevant to your work. What could a project be about that would make each source relevant firsthand information? Our answers are at the bottom of the page, but remember that there are many more–including the ones you think of that we didn’t!

  1. Fallingwater, a Pennsylvania home, designed and constructed by Frank Lloyd Wright in the 1930s.
  2. Poet W.H. Auden’s elegy for Y.S. Yeats.
  3. An arrowhead made by (Florida) Seminole Native Americans but found at Flint Ridge outside Columbus, Ohio.
  4. E-mail between the U.S. ambassador to the United Nations, Nikki Haley, and her staff about North Korea.
  5. A marriage license.


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, which usually means journal articles in the sciences. If they are called primary sources in the sciences, it’s usually because the researchers got their information primarily from those sources.

What is 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. After all, that’s a primary source!


  1. You are doing a study of the entrances Wright designed for homes, which were smaller than other architects of the time typically designed entrances.
  2. Your research project is about the Auden-Yeats relationship.
  3. Your research project is about trade among 19th-century Native Americans east of the Mississippi River.
  4. Your research project is on how Ambassador Haley conveyed a decision about North Korea to her staff.
  5. You are writing about the life of a person who claimed to have married several times, and you need more than her statements about when those marriages took place and to whom.



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Choosing & Using Sources: A Guide to Academic Research Copyright © 2015 by Teaching & Learning, Ohio State University Libraries is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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