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BIOL 120: Intro to Biological Inquiry: Primary & Review Articles

Primary Sources Video (2:51 mins)

Primary, Secondary, Tertiary Sources Defined


  • Are first-hand accounts or individual representations and creative works.
  • Are created by those who have directly witnessed what they are describing.
  • Bring us as close to the original event or thought as possible without being filtered, influenced or analyzed through interpretation.
  • Tend to be original documents that do not usually describe or analyze work by others.
  • May be published or unpublished works.
  • Follow scientific format that include: methods, results, & discussion


  • Words and phrases in the title and abstract should tip you off:
    • In our experiment, our results, our data, our methods, we found/discovered
  • If you can't determine if it is original research, treat it as a review or secondary source. 


  • To provide your own original analysis.
  • To make claims or criticisms.
  • To provide direct evidence for theories.
  • To gain timely perspectives on a topic.
  • To verify the original source of information.
  • To investigate how an experiment was done.


  • General Examples: Letters, diaries, speeches, interviews, correspondence, court cases, newspaper articles about current events.
  • Natural & Physical Sciences: Analyzed results from original studies, field data, experiments and research.
  • History: Transcript of a speech; newsreel and video footage.
  • Literature: Original literary works such as books, short stories, and poetry.
  • Art: Art works by artists.
  • Social Sciences: Interview transcripts of patients; raw, unanalyzed population data; newspaper articles about events.


  • Are second-hand analyses of other peoples' works.
  • Offer extensive and in-depth analyses of primary sources.
  • Summarize, evaluate, and analytically interpret primary material.
  • Are not evidence, but are useful sources of  different experts' views of the primary sources.
  • Are one step removed from the original or primary source. 
  • Are published works, that list their sources of information which can be then used to locate additional information for your research.



  • Words and phrases in the title and abstract should tip you off:
    • In our review
    • Annual Review of...
  • If you can't determine if it is original research, treat it as a review or secondary source. 



  • To summarize, analyze, or evaluate a primary source.
  • To provide background information.
  • To give an outside or neutral perspective.
  • To place first hand experiences into a broader context.
  • To support or contrast your work in relation to existing research.


  • General Examples: Textbooks, scholarly books, analyses, review articles, dissertations, theses.
  • Natural & Physical Sciences: Articles that reviews and evaluates the theories and works of others
  • History:  Article analyzing a speech; book recounting battle history; biographies.
  • Literature: Literary critiques that examine writing style and techniques.
  • Art: Lecture given about and artist's techniques; criticism or a review of artist's work.
  • Social Sciences: News commentaries; articles analyzing results of a study; a book that discusses population trends over time; evaluations of social and government policy, law and legislation.


  • Are factual distillations and collections of primary and secondary sources.
  • Present a summarized factual representation of information.
  • Are free from biased points of view and critiques.
  • Are the last documents to be published in the information cycle. 
  • Tend to consist of highly reliable and accurate information,
  • Contain broad perspectives of topics. 
  • Offer a general overview of your topic and background information for your research.



  • When factual information is needed
  • When basic information is needed.
  • When definitions or statistics are needed.


  • General Examples: Handbooks, encyclopedias, dictionaries, directories, classification systems, chronologies, almanacs, atlases, guidebooks, manuals, spectroscopy tables, and other factbooks.