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Biology 301: Primary, Secondary & Tertiary Sources

Primary Sources

Primary sources of information are original materials that often convey new ideas, discoveries, or information. These sources originate from the time period under study. Examples of primary sources include:

  • original research studies (often in the form of journal articles in peer-reviewed publications), also called empirical studies (e.g. psychology)
  • patents, technical reports
  • original documents such as diaries, letters, emails, manuscripts, lab data/notes
  • newspaper articles from the time period under study
  • autobiographies, first-person accounts, case studies
  • artifacts and archival material such as official documents, minutes recorded by government agencies and organizations, photographs, coins, fossils, natural specimens
  • works of art such as literature, music, architecture, or painting

TIP:  What is considered primary, secondary, or tertiary information may vary according to your field of study. When in doubt, ask your professor.

Secondary Sources

Secondary sources of information are based on primary sources. They are generally written at a later date and provide some discussion, analysis, or interpretation of the original primary source. Examples of secondary sources include:

  • review articles or analyses of research studies about the same topic (also often in peer-reviewed publications)
  • biographies, reviews, or critiques of an author
  • analyses of original documents or archival material

    Tertiary Sources

    Tertiary sources of information are based on a collection of primary and secondary sources. Examples of tertiary sources include:

    • textbooks (sometimes considered as secondary sources)
    • dictionaries and encyclopedias
    • manuals, guidebooks, directories, almanacs
    • indexes and bibliographies

    Flow of Scientific Information