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Library Orientation/N602 Epidemiology for Orange Campus

Boolean Operator

  • Use AND in a search to narrow your results. ALL search terms must be present in the resulting records. (e.g. rental control AND San Francisco)
  • Use OR in a search to widen your results. ANY of your search terms can be present in the resulting records. (e.g. automobile OR car OR van)
  • Use NOT in a search to narrow your results by EXCLUDE the records containing the search terms.  (e.g. Jaguar NOT car)

Boolean Operators


  • widen your search to include various word endings and spellings
  • truncation symbols * is the most widely used. However, it may vary by database: *, !, ?, or #.  

child* = child, childs, children, childrens, childhood



  • widen your search  by substitute a symbol for one letter of a word.
  • This is useful if a word is spelled in different ways, but still has the same meaning.

wom!n = woman, women
colo?r = color, colour




  • narrow your search by specify that adjacent words be searched as phrases.
  • not all databases support use parentheses

"genetic engineering"



Other Tips

  • Databases can only word match. Different from popular search engines, such as Google, most academic databases do not interpret your search questions or correct spelling.
  • Databases look for the exact words and phrases you type in.
  • Break your research question into several key concepts, search terms or keywords. Brainstorm the words an author may use to describe the key concepts.
  • Place each search term into individual search box. Refine your search by using different Boolean operators.