George Mason University

Combining Keywords

Once you've identified appropriate keywords and phrases that describe your topic, the next step is to plug these into a database or search engine to find the information you need.

Search engines like Google allow you to simply enter keywords and phrases to conduct a search.

Google

However, library databases work a bit differently. Keywords and phrases often need to be connected using Boolean operators: AND, OR, and NOT. Boolean operators are used to broaden and narrow keyword searches.

Separate concepts with AND
boolean

The operator AND is used to combine different keywords in a search. Inserting AND between your keywords allows you to search for more than one concept at a time. Use AND when you want to narrow search results.

Example: If your research question is "Many college students work while going to school. Does their working have any effect on their grades?" your search string might include:

college students AND working AND grades

This search allows you to retrieve documents that contain the terms college students, working, and grades.

Boolean Example
Combine synonyms with OR
Boolean

The operator OR is used to find synonyms of search terms. Add OR when you want to broaden search results.

Example: A new search string for the search above might include synonyms for the term "working."

working OR employment OR jobs

This search allows you to retrieve documents that contain not only the term "working," but also "jobs" or
"employment" retrieving an additional 19 documents.

Example in ASC
Connecting terms with AND and OR

Connect synonyms into one set using OR, and connect separate concepts using AND.

Example: (college students OR undergraduates) AND (working OR employment OR jobs) AND grades.

boolean example in asc

This search was done in the database Academic Search complete. Remember you can use boolean operators in most catalogs and database; however, there may be slight differences from resource to resource.

For instance, some databases, like Sociological Abstracts, may only present you with one search box. In this case, you must use proper search syntax. Surround synonyms with parentheses and separate with the AND operator. You may also need to surround exact phrases, like "college students," with quotation marks.

basic search string

If you're having trouble with search strategies for a particular database, look for a Help page or Search Tips section. These pages are usually linked to from the main search screen of a database.

Use truncation symbols (? * #) to search for multiple endings

truncation symbols

Truncation is a search strategy that allows you to search for words that start the same but have multiple endings like "crime," "criminal," and "criminals." Not all databases use the same truncation syntax! Usually, you need to look at the "help" screen to find out what symbol it uses. Three common truncation, or "wildcard," symbols are: ? * # Using truncation can simplify your search string.

Example:
Before: (college students OR undergraduates) AND (working OR employment) AND grades.
After: (work* OR employment)

For more assistance with combining keywords, Ask a Librarian.