Department of Library Services

Searching with Boolean Operators & Wildcards (truncation)

The Boolean operators AND, OR and NOT combine the relationships between words or groups of words in a search strategy. By applying Boolean operators with your keywords you will be able to execute a much more powerful search than only using phrases or natural language.

Use Boolean operators with databases, the library catalogue and search engines. Consult the Help option of the database or search engine on how to conduct effective searches and retrieve accurate results.

For help on searching with GoogleScholar™, use the Google™ Cheat Sheet

Operator

How the operator works

AND

Use AND to retrieve records containing both search terms: all terms must be included in the record.
Use AND to narrow your search and retrieve fewer records.

Example 1: hydrodynamics AND viscosity retrieves records containing both the keywords.
Example 2: elephants AND lions retrieve records containing both the keywords.

Use OR to retrieve records containing either or both search terms.
Use OR to broaden your search and retrieve a greater number of records.
Use OR for synonyms or spelling variations.

Example 1: milk OR dairy retrieves records containing either milk or dairy, or both the keywords.
Example 2: citrus OR oranges OR navels
Example 3: behavior OR behaviour

NOT

Use NOT to exclude certain items from your search.
Caution: It is easy to exclude relevant terms; use the NOT operator with care!

Example 1: pathogens AND plants NOT human excludes all records where pathogens are related to human diseases.
Example 2: learning AND adults NOT children retrieves records which focus on adult learning.

ADJACENT/ NEAR/ SAME

(Proximity Operators)

Proximity operators (variations of the basic Boolean operators), are supported by library abstract databases. Consult each database's Help for tips on how to apply proximity operators in that specific database. E.g. ISI Web of Knowledge use the SAME operator while other databases apply the NEAR operator.
Use the proximity operators only when you retrieve too many records where the keywords are not closely related to each other.

ADJACENT requires that the words appear next to each other.
NEAR or SAME require that the search terms appear in close proximity or in the same sentence.

TRUNCATION/ WILDCARDS

Truncation allows the searcher to insert a truncation symbol, usually an * or ?

Example 1: teen* will retrieve records with the terms teens, teenagers, and teenaged.
Example 2: econom* will retrieve records with the terms economics, economically, economize, economise, etc.
Example 3: wom?n will retrieve women or woman.

PARENTHESES (NESTING)

When combining different Boolean operators, use parentheses to group the search terms.

Example 1: (bridge* OR tower*) AND (construct* OR design*) AND concrete
Example 2: ((team* OR organi*) AND climate) AND perception*

Acknowledgement: Marié Theron, 2005.

Help

Still need help? Please contact Ask a Librarian or your Information Specialist.