Related Library Research Guides

An Overview of Biological Literature

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

Search tip: Did the authors themselves collect or analyze data? If the answer is yes, it is probably primary research.





Secondary Sources

Summaries, evaluations, or interpretations of others' research

Examples: Review articles, Book reviews, Annotated bibliographies

Search tip: Scholarly review articles are usually easier to understand than the primary literature. Try adding the term "review" to your search strategy to find them. 





Tertiary Sources

Collections and summaries of primary and secondary sources

Examples: Reference books, Dictionaries, Encyclopedias

Search tip: Try searching in ESearch for reference materials


Differentiating Research and Review Articles

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. Here is an example of a research article:


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. Here is an example of a review article:

Library Esearch

Try ESearch for a quick search of a little of everything. You can then limit your results using the filters. Find tips on searching for articles in ESearch here

Esearch logo  

Citing Sources

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Kelly Getz
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