Advanced Search Techniques

Boolean Basics

Boolean operators define the relationship between search terms.

• AND searches for all of the search terms. The AND operator limits the search because the sources in the results must contain both terms.
• OR searches for either of the search terms. The OR operator expands the search because the sources in the results can contain either term.
• NOT excludes the search term immediately after the NOT operator. The NOT operator limits the search because the sources in the results cannot include the term following the word NOT.

Boolean Examples

diabetes AND children = articles about children with diabetes
diabetes OR children = articles about either diabetes or children 
diabetes NOT children = articles about diabetes, but excludes articles mentioning children with diabetes

This diagram will show you how the Boolean operators limit or expand searches.

Image attribution: CC BY-SA 4.0 by Cecelia Vetter

For more help, watch this video on Using Boolean Operators:

Boolean Modifiers can be used to further refine your search. 

• The asterisk *, also called the wildcard or truncation, searches for all forms of the word stem.
  • For example, searching nurs* would return results for nurse, nurses, nursing, etc. 
  •  Searching for statistic* would return results for statistic, statistics, statistical, etc. 
• The parentheses () are used around OR statements to ensure the database recognizes which terms are encapsulated in the OR statement. 
  • For example, if you're expanding your search to encapsulate three similar keywords, you can put parentheses around the whole statement like so: (high school OR secondary school OR senior high school)
• Quotation marks " " are used to return results with the exact term inside the quotation marks.
  • For example, if you search "bird" you will only get results that contain the word "bird," but not words like birds or birding.