What are Primary, Secondary, and Tertiary Sources in Biology Research?

Biological information exists in different formats including: articles, books, and data. Sources can be primary, secondary, or tertiary. Authors of primary sources analyze data. Secondary and tertiary sources interpret and summarize other sources. Primary sources are often the most up-to-date, but can be difficult to read and understand. Secondary and tertiary sources are often easier to understand, but have undergone additional interpretation. 

Primary Sources

Original research, evidence, and analysis

Examples: Research articles, Patents, Research data, Lab notes, Conference presentations, Clinical trials, Original models





Secondary Sources

Summaries, evaluations, or interpretations of others' research

Examples: Review articles, Book reviews, Annotated bibliographies






Tertiary Sources

Collections and summaries of primary and secondary sources

Examples: Reference books, Dictionaries, Encyclopedias



What is the Difference Between Research and Review Articles? 

Scientific research builds on the work of others.

Scientists share the methods, results, and conclusions of their research investigations through research articles. Most research articles are considered scholarly and undergo the peer-review process. Through the peer-review process, experts in the field evaluate the articles prior to publication. Research articles that have not undergone peer-review might not be reliable

Review articles are another commonly used type of scientific literature. Authors of review articles read current research articles written by other authors then summarize or evaluate the information. Review articles often also undergo the peer-review process. 


How to Identify a Research Article 

  • Research articles are primary sources.
  • The authors of the article have conducted an original analysis of primary data (data they collected) or secondary data (data someone else collected).
  • Research articles have section labels that are similar to lab reports such as: Introduction, Methods, Results, Discussion, and Conclusion. Research articles often include some data in the form of tables or some representation of data in the form of charts, graphs, or other visualizations.

Example of a research article:

Gmutza, H. J., Foster, R. W., Gmutza, J. M., Carter, G. G., & Kurta, A. (2024). Survival of hibernating little brown bats that are unaffected by white-nose syndrome: Using thermal cameras to understand arousal behavior. Plos one19(2), e0297871.


How to Identify a Review Article  

  • Review articles are secondary sources.
  • They summarize or reorganize information that was published in other articles.
  • They often have section labels that are more specific to the topic.

Example of a review article: 

Nyffeler, M., & Altig, R. (2020). Spiders as frog-eaters: a global perspective. The Journal of Arachnology48(1), 26-42. 


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