Skip to Main Content
It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.

NURS 6320 - Theoretical Foundations: Find Theories

Access the Databases

Browse an alphabetical list of all databases, or search by name: CINAHL, PubMed.

Boolean Operators

What are Boolean Operators?

Combine your search terms using Boolean operators to get results. Boolean operators connect your search words together to either narrow or broaden your results in a database (like PubMed) or search engine (like Google Scholar).

Boolean operators are the words "AND", "OR" and "NOT".

Diagram Explaining Boolean Operators


  Prefer a video? Watch this Boolean Operators tutorial.

Identifying Theories Using Databases

Remember to use the [TW] tag with "theory," and then use Boolean Operators to combine with topic of interest.


An image showing the history of a search in PubMed combining theory as a text word and keywords of interest.

Remember to use SUBJECT HEADINGS to help make searching easier. Most citations in CINAHL are indexed.


An image showing how the term "theory" is indexed in the CINAHL subject tree.

Use Boolean Operators to combine with your topic of interest and check the subject headings.

An image showing a search history in CINAHL combining the subject heading "Theory" with keywords for multiculturalism.>

Using the Advanced Search feature of Google Scholar gives the user more control over results.


An image showing the advanced search box in Google Scholar.