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Effective Literature Searching: Boolean Operators

Learn how to perform an effective literature search by translating a research question into a search strategy in a database such as PubMed

Boolean Operators

Boolean Operators

Linking your concepts correctly will help you find the most suitable results. Many databases, including PubMed employ "Boolean operators." Boolean operators are words that connect search terms together to broaden or narrow the results retrieved.

The three Boolean operators are AND, OR, and NOT.

  • AND narrows your search by limiting your results to items that contain both words connected with AND.
  • OR expands your search by including results that contain one word, the other word, or both words.
  • NOT narrows your search by limiting your results to items that contain the word you designate before NOT, but not the word after NOT.

Cecelia Vetter, CC BY-SA 4.0, via Wikimedia Commons

Attribution: Cecelia Vetter, CC BY-SA 4.0, via Wikimedia Commons