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Evaluating Sources: Source Classification

A guide to evaluating sources.

Source Types

One way that we organize sources is based on their content. For this type of classification, we label them as primary sources, secondary sources, and tertiary sources.

Another way that sources are organized is by their publication type. The three main publication types are books, periodicals, and websites

When identifying source types, you can use both primary, secondary, and tertiary AND the publication type. For example, many things are published as books, such as diaries (primary sources), monographs (secondary sources), almanacs (tertiary sources), etc.

Primary Sources

  • Primary sources are the evidence of history, original records or objects created by participants or observers at the time historical events occurred or even well after events, as in memoirs and oral histories. (RUSA, n.d.)
  • What classifies as a primary source depends on the discipline of study.
    • In History, a primary source could be an account of the event by someone who witnessed it or an account that was recorded at the time of the event.
    • In the Sciences, data sets from an experiment are considered a primary source.
    • In the Social Sciences, information like census data or statistics are considered primary sources.
    • In Literature, novels, poems, and plays are considered primary sources.
  • Examples of Primary Sources (Hint: These are keywords you can use in a search to help you locate a primary source!)
    • Autobiography
    • Diary/Diaries
    • Letters
    • Interview
    • Personal Narratives

Secondary Sources

  • A secondary source is a source that uses primary sources as evidence to make a point or argument 
  • In a secondary source, there might be some analysis, but it is not necessary to be a secondary source.
  • When you write about something that someone else wrote about (in a primary source) what you are writing is a secondary source.
  • There are many publication types that are secondary sources, but the best examples are:
    • books
    • journal articles
  • When searching for secondary sources, use words like:
    • analysis
    • comparison
    • criticism

Tertiary Sources

  • A tertiary source is a source that provides background information.
    • Note: Sometimes tertiary sources are lumped in with secondary sources, rather than having their own category.
  • Tertiary sources compile, analyze, and summarize multiple secondary sources.
  • They are different from secondary sources because they give you just enough information to get you started on your research - they provide a broad overview.
  • They are not in-depth or current enough to be used as a source for scholarly research.
  • Examples of Tertiary Sources (Hint: These are keywords to look for to try and determine if something is a tertiary source or not)
    • Encyclopedia
    • Dictionary
    • Reference Books
    • Atlas
    • Textbook


  • Can be published in print and/or electronically
  • Longer works
  • Might be a scholarly text, collection of poetry, fiction, memoirs, or other information.
  • Often divided into chapters or sections, but not always
    • A chapter of a book might be a source on its own—many people cite chapters of books individually
  • Types of books
    • Monographs
      • A detailed, written study on a specialized subject written by academics for academics
    • Anthologies
      • Poetry & fiction
      • Scholarly anthologies
        • Chapters written by different authors about one central topic
        • Chapter may have been published previously as a journal article


  • Any source that is published on an ongoing, regular basis (or periodically).
  • Can be published in print and/or electronically
  • Types:
    • Newspapers
      • Contains factual information (hopefully) about events soon after the event occurs.
      • Written for non-scholarly audiences by journalists and (usually) published daily.
    • Magazines
      • Popular sources, more in-depth than newspaper stories, but still written by journalists
      • Written for non-scholarly audiences and are usually published weekly.
      • Might center on the news or have a specific area of interest (e.g. Vogue caters to people with an interest in fashion).
    • Journals
      • Collections of academic (nonfiction) articles usually about research or professional activity.
      • Often have a focus on a specific discipline (e.g. Stanford Law Review)
      • Some go through a process called peer review, while others do not
        • Peer review is a process in which experts in the author’s field read a piece of scholarship to determine if the research is sound and appropriate, and that something new or useful is being contributed to the field.
      • Usually published a few times a year


  • A website is an internet location consisting of one or more pages that contain information that was not previously published as another source type.
    • Can be almost anything: blogs, government websites, nonprofit organization websites, library websites, etc.
      • Note: Electronic newspapers or magazines should be cited as newspapers or magazines even when they are available on a website.