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Primary Sources in the Sciences

Primary, Secondary, and Tertiary Sources in the Sciences

Primary Sources Secondary Sources Tertiary Sources*

Provide the original findings, results, or data from research, studies, observations, and experiments that have been generated by a researcher. 

Produce or compiled from information originally reported in primary sources. Secondary sources may summarize a single piece of research, provide a general overview of a topic, or review a collection of research on a specific topic over a period of years. 

Derive their information from primary or secondary sources. 

Examples of published primary sources

  • journal articles
  • technical reports
  • Conference papers (proceedings)
  • Theses & dissertations
  • Patents

Examples of unpublished primary sources

  • field notes
  • interviews
  • letters/correspondence
  • specimens (e.g. plants)
  • lab notebooks & diaries


  • books (e.g. textbooks)
  • science magazines (e.g. Scientific American, New Scientist)
  • review articles (e.g. in journals)
  • reference materials (e.g. encyclopedias, dictionaries) and handbooks (e.g. CRC handbook of chemistry & physics)


  • manuals
  • almanacs
  • bibliographies
  • chronologies
  • handbooks (fact books, data books, constants)
  • dictionaries
  • encyclopedias
  • directories

*Most researchers and authors within the various science disciplines agree on what constitutes a primary source in their fields. However, distinguishing between secondary and tertiary sources is more problematic and can be widely disputed among researchers, authors, and science librarians.

Disagreement about secondary versus tertiary sources in the sciences seems to originate from determining whether the source of information goes through one or two levels of distillation. Secondary sources derive their information from primary sources (one distillation), whereas authors who support a more extensive list of tertiary sources state that tertiary sources derive their information from either primary or secondary sources. The latter would then require two distillations prior to publication. Since both categories use information originally published in primary sources, the distinction between secondary and tertiary sources becomes somewhat moot, nor does this distinction impact their usefulness as information sources.

Students may wish to check with specific course instructors regarding which option they use.

Related Guide

Science & Technology: Guides

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