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Our Helpful Reference Guide for Primary and Secondary Sources


Almost all kinds of writing will at one point require you to take on that dreaded task: research. Whether you're writing a thesis on historical trade deficits, an article on a new type of smartphone, or crafting a novel on the life of Berliners in the 1960s, you will need to consult various types of reference materials to make sure your writing is based in fact.

Reference materials help ensure your writing is based in fact.
Reference materials help ensure your writing is based in fact. Photo by Donna Lay on Unsplash.

Before you jump in, know that not all sources are created equal. For each new source you come across, whether it's a journal, textbook, letter, photograph, or anything else, you will need to determine if it is a primary or secondary source.

Primary sources refer to sources that provide direct and firsthand evidence on whatever you are researching. These are the lifeblood of all good writing. They bring you as close as you can possibly get to your subject, offering details and insights you won't be able to find anywhere else.

Secondary sources refer to sources that provide analysis or interpretation of those primary sources. These can be useful as well, giving you a wider perspective and pointing you in helpful directions in your research. They will always be at least one degree removed from your subject, though.

Think of the difference between these types of sources as the difference between your friend telling you a story that happened to them and a story they heard about someone else. The former is going to be a more vivid account because your friend experienced it firsthand. When it comes to your research, relying on primary sources means gaining a detailed and precise understanding of what you want to write about.

Below we go into more detail on each of these sources, including what they are, how to tell them apart, and when you should use them.

Primary sources

A primary source is any source that provides you with firsthand knowledge on a given subject. For instance, if you're writing about Mark Twain, this could mean an interview with Twain, letters Twain wrote to friends, or a speech or lecture Twain gave. Each of these items provides you with direct access to Twain's life and thoughts.

Contrast this with a biography of Mark Twain written after his death. While the author may have consulted primary sources when writing it, they themselves had no firsthand knowledge of Twain. Even a review of one of Twain's books written during his lifetime would not be a primary source, unless the author had a personal relationship or interaction with Twain.

These sources extend to any type of subject. If you are writing on a certain time period, a primary source would be any document written during that time or by people who lived through it, such as a diary, letter, or an artifact like a business ledger. If you are writing about a certain type of cooking method, a primary source could be a video of that method, interviews with people who practice it, or you could become your own primary source and go watch it firsthand.

Examples of primary sources include:

  • Memoirs and autobiographies
  • Interviews
  • Videos and photographs
  • Letters and diaries
  • Novels, poems, paintings, and other art
  • Government records
  • Laws, court decisions, and other legal texts
  • Primary research papers
  • Raw statistical data
  • Physical artifacts

One consideration when evaluating primary sources is how close they are to your subject. Videos and photographs give you an immediate image of your subject. Letters put you in the mind of the person you want to learn more about. However, if you are reading someone's memoirs, they could be recounting events from years or even decades in the past. You are still learning about those events from a primary source, but the information you receive will still be at a distance.

It's also important to consider where you can find the sources you need. Items like letters, diaries, and government documents aren't always available online, or if they are they may come at a cost. Things get even harder when you're looking for primary sources from far in the past. In these cases, it's a good idea to check with your local library to see what they have available. You may also be able to join a nearby university library and see what research services they offer. Many online subscription services also provide access to rare documents and articles.

Secondary sources

A secondary source provides insight into a given subject without having any direct or firsthand knowledge of it. An example of this would be the Mark Twain biography cited above. While the biographer certainly consulted numerous primary sources, unless he or she knew Mark Twain directly it would still be a secondary source. Another example would be a critical analysis of Mark Twain's novels. Again, the author brought together primary sources (the writings of Mark Twain) to create a new work of scholarship. Each of these items provides insight into the life and work of Mark Twain but does not offer a direct perspective.

This isn't to say that secondary sources are bad or that you shouldn't use them. A secondary source can be a vital tool toward understanding your subject in a new light or identifying useful trends. They can also help organize and categorize primary source material, such as an encyclopedia or an analysis of quantitative studies in a given area. This can also be a helpful tool to learn about new primary source materials you might not know about or gain information on sources you may not have access to. Just remember, if your secondary source gives you information on a new primary source, don't stop there. Your new task is going and finding that new primary source for yourself.

Examples of secondary source materials include:

  • Biographies
  • Textbooks
  • Encyclopedias
  • Newspapers and magazines
  • Policy summaries
  • Documentaries about a historical event
  • Literature reviews
  • Art and literature criticism

When it comes time to write, remember that these aren't the sources you want to be drawing from for key facts and details on your subject. It's best to keep your secondary sources as a background tool to help you go deeper in your research.

How do you tell which is which?

At this point this shouldn't feel complicated. Right? That depends on what you're researching. Think of a review of a play. At first thought, this sounds like a secondary source, particularly if you're studying the playwright. The review is a critique of the playwright's work by a secondhand observer, so it would count as a secondary source.

However, what if your research subject was the critical reception of their plays? Or the critic themselves? Since the review addresses your subject by someone with firsthand knowledge, it is now a primary source.

Here are some more scenarios where identifying which kind of source it is can be tricky:

  • A documentary on a subject you are researching would be a secondary source. However, if your subject is the director, or the techniques used in making the documentary, then it is a primary source.
  • A politician's speech on a certain law would be a secondary source if you are researching that law. However, if you are researching partisan reactions to the law, it becomes a primary source.
  • A newspaper or magazine article about a historical event would be a secondary source. However, an article about an event soon after it happened, or, even better, from a journalist who personally watched the events occur, would be a primary source.

For each source, always ask yourself: is this author directly involved with what I am researching? Are they providing me information firsthand, or are they describing what they heard or read from somewhere else? Going through this process for each source will help make sure you understand what kind of material you have and how to best apply it to your writing.

A newspaper or magazine article about a historical event would be a secondary source. However, an article about an event soon after it happened, or, even better, from a journalist who personally watched the events occur, would be a primary source.
A newspaper or magazine article about a historical event would be a secondary source. However, an article about an event soon after it happened, or, even better, from a journalist who personally watched the events occur, would be a primary source. Photo by Yang Xia on Unsplash.

Which should you use?

For any given research project, you will need to consult both primary and secondary sources. But that doesn't mean you should give them equal weight. As discussed above, primary sources give you the freshest and most direct information available on what you're studying. They offer you insight and detail that a secondhand source simply wouldn't have. Just think, what would be a more enriching experience: seeing a movie, or hearing someone describe a movie?

This is why you should always prioritize using primary sources whenever possible. If you want to learn what life was like in Colonial America, skip the textbooks and see if you can find diary entries and letters from colonists. If you want to learn more about how the Clean Air Act works, don't look at summaries of the policy, go and read the actual policy. Going to the source rather than relying on analyses or summaries has the additional benefit of allowing you to draw your own conclusions rather than get your information filtered through someone else's.

Though don't think this means that you should skip secondary sources altogether. As discussed above, these kinds of sources have their own benefits, particularly at the beginning of the research process. They help broaden your net and see things from different perspectives. Most importantly, they point you in the direction of primary sources you may not have even known about.

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