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Library Research: Types of Sources

A general overview of library research.

Saint Paul College Library

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What is Peer Review?

Peer review is the evaluation of scientific, academic, or professional work by others working in the same field. When an article states it is "peer reviewed," it means other experts who study the same subject read the article, commented on it, and approved it before it was published.

The ultimate purpose of peer review is to help maintain the integrity of the field by rejecting unoriginal or invalid articles, and encouraging scholars to submit high-quality work for publication. 

Types of Sources

First of all, what is a source? A source, by definition, is where someone or something came from: the original version of something. Sources can be many things: newspapers, podcasts, diaries, blogs, films, musical recordings, etc., but in most academic settings, sources are the materials from which a writer gathers their thoughts and ideas, like books and journals. Those sources can generally be divided into two categories: scholarly and popular. 

Scholarly sources are in-depth accounts of findings written by qualified researchers. They use very specific language, and it can feel like they are written for people who already have a thorough understanding of the subject and its vocabulary. A scholarly article usually has a long list of references at the end, and is most often found in an academic journal or a book. Scholarly articles can also be called peer-reviewed articles because the publication process includes being evaluated by other experts in the same field. Scholarly or peer-reviewed articles are most likely what your professor will ask you to use for your assignments. 

Examples of scholarly sources: 

  • Journal of Information Literacy
  • Annals of Mathematics
  • Journal of the History of Biology
  • Southwest Review

Popular sources are designed to provide information to a broader audience. They may include personal narratives or opinions, and they are generally meant to entertain and/or inform. Popular sources are usually attractively designed, illustrated with glossy images, and many contain advertisements interspersed through their pages. They are not as dense as scholarly articles, use language meant to be understood by non-experts, and most likely have no citations at the end of articles. 

Examples of popular sources:

  • Teen Vogue
  • Sports Illustrated
  • Better Homes & Gardens
  • Men's Health

The video below will give you more tips for deciding whether your source is popular or scholarly. 
(“Scholarly and Popular Sources” by Carnegie Vincent Library is licensed under CC BY)

Primary vs. Secondary vs. Tertiary

Knowing whether your source is primary, secondary, or tertiary will help you understand the perspective of the information you're using. Understanding who created the sources you're using, why the source was created, and how that source is viewed by others is key to understanding how information shapes the world we live in. 

  • Primary sources are original materials or first-hand accounts. They are generally created at the time an event takes place and come from the perspective of someone directly involved with or affected by an event. 
  • Secondary sources are created after an event has occurred and come from a secondhand perspective. These sources can provide background information or outside analysis of the event. Secondary sources often offer different perspectives than primary sources, and can place primary sources into a historical context. 
  • Tertiary sources are summaries, distillations, or indexes of material. These sources often link back to primary sources, and can sometimes help you understand the background and context of the original source. Tertiary sources tend to be factual, like encyclopedias, guidebooks, or dictionaries. 
Understanding Primary, Secondary, and Tertiary Sources
Primary Secondary Tertiary
a novel a review of the novel an encyclopedia of authors
a World War I diary a documentary about World War I an index of World War I battle locations
a Harvey Girl uniform from 1880 a news article on Harvey Houses a museum collection of women's uniforms through history
notes taken by a psychologist an article about the psychological condition a clinical psychology textbook
letters written by John Lewis a website analyzing John Lewis' speeches an encyclopedia of Civil Rights Activists