Types of Sources

In order to determine what kinds of sources you need, you need to carefully read the prompt and review your research question.

  • Do you need basic facts and a broad overview on a topic?
  • Do you need a first-hand account or raw data produced from a certain event?
  • Do you need analysis that considers multiple first-hand accounts and the work of multiple scholars?

Each of these questions directs you towards a different type of source (tertiary, primary, secondary). Often you’ll want to use several of these types in any given paper. Let’s look more closely at each of these categories and see how they could be useful for you.

1. Does this project require basic facts and a broad overview on a topic?


  • What kinds of algae are most frequently found in Lake Erie?
  • How many miles of trenches were built during the First World War?
  • What happened geologically during the eruption of Mt. Vesuvius?
  • Who gave speeches at the Republican National Convention in 2012?

If your project requires information of this kind, you’ll probably want to start with a tertiary source.

tertiary iconTertiary sources (as opposed to primary or secondary sources) are encyclopedias, dictionaries, etc; they compile information from trusted experts and produce short entries on each item. Tertiary sources provide you with basic information that you might need to proceed with your project, and they can help you hone your research question. Often they can also lead you to other valuable sources. Most likely, you’ll begin with this broad overview but later drill down into something more specific.


The tertiary source you are probably most familiar with is Wikipedia. The jury’s still out on the validity of Wikipedia as an academic source: some of your professors will allow it, while others will tell you to avoid it at all costs. Why? The difference between Wikipedia and other tertiary sources is that Wikipedia is crowd-sourced, which means that anyone–anyone!–can change and edit entries. Usually people edit entries to make them more accurate, but sometimes people do so as a joke. And sometimes even factually accurate entries are poorly organized or poorly written. Wikipedia can be a useful place to start, though, because it can give you general background on a topic. Also, since the strongest Wikipedia entries reference the information they use, they can point you to other, more trustworthy sources. Look at the list of citations at the bottom of an article: do any of the listed sources seem useful to you? It’s always better to examine multiple sources instead of relying on one source alone.

2. Do you need a first-hand account or raw data?


  • What were the rates of algae production in Lake Erie between 2004 and 2014?
  • How did English soldiers write about life in the trenches during World War I?
  • What was the composition of core samples taken during a 2009 geological survey at Mount Vesuvius?
  • How did Latino-Americans react to the political speeches at the Republican National Convention in 2012?

primary iconIf your project requires first-hand experience or raw data, you’ll want to look at primary sources. Primary sources were generally created at the time that people experienced an event. In the sciences, they include databases and experiment result data. In the humanities, they include letters, diaries, newspaper accounts, interviews, poems, novels, visual art, and movies.

3. Do you need analysis that synthesizes multiple first-hand accounts and the work of multiple scholars?


  • How have increased levels of algae affected the fishing industry on Lake Erie?
  • How did soldiers’ experience of the trenches in World War I influence post-war European culture?
  • How did the eruption of Mt. Vesuvius reshape the Italian coastline?
  • What did polls from the summer and fall of 2012 determine about Latino-Americans’ perception of the Republican Party?

secondary iconThese questions require you to examine how other scholars have approached your topic. To do this, you will have to look at secondary sources. These include academic books and articles (or electronic copies of print books and journals), and occasionally online publications.

Secondary sources usually analyze raw data and present conclusions about it. Before you can trust those conclusions, you have to know whether other experts on this topic would view them as reputable. This isn’t the same as agreeing or disagreeing with the author’s conclusions. Before you can even get to that point, you have to know that the conclusions were reached by someone who has enough expertise to draw valid conclusions on this topic.

Academic publishing is built around peer review–a process in which an author’s manuscript or article must be approved by a series of experts before it is published. Other systems, such as self-publishing or blog posts, may not require any expert oversight at all.

Knowing how your source was published (By University of Michigan Press? By your grandpa in his basement office? By a big publisher who specializes in romance novels?) can help you determine how reliable the facts and arguments provided in your source are.


Academic publishing is also a good source because you can easily get information on how the author got their information–where data came from, who funds their work, what sources they used. Journalists, for example, don’t always cite their sources, which can make it harder to verify what they have said, or figure out where they got their information.