Boolean Searching GuideMost databases allow the use of AND, OR and NOT to broaden or narrow a search. 

  • AND will narrow the search to include only records with both terms. 
  • OR will broaden the search to include records with either term.
  • NOT will narrow the search to exclude records with one of the terms.

Truncation:  You can use an * at the end of a word stem to broaden your search to include related terms.  For example, to search for child, children or childhood use the search term child*

Putting quotes "" around words allows you to search for a phrase.  For example, searching language development, without quotes, finds records with both the word 'language' and 'development' somewhere in the record.  Searching "language development", with quotes, only find records with the phrase "language development".


Example: How does bilingualism affect language development in children?


searching how bilingualism or multilingualism affect language development in children?


NOTE:  When you begin doing advanced searching in a new database, look for the Help or Information sections to determine how that database works, and how it may differ from other databases with which you are familiar.

The value of citation searching

Use articles you've found to find more relevant material by looking at what they cited.

An excellent way of discovering new and relevant resources is to use the articles that you have already identified as important works in you search.  The articles and resources in the references or bibliography can point you to other relevant sources that were published prior to the article of interest. 

But how do you find more recent articles that have used and cited the article of interest in their work?


Web of Science is a database of scholarly literature that also tracks citations and allows citation searching.  In the search results window you can sort by times cited and view the articles that are citing a specific work.

Sort by Times Cited to find the most important works on a topic and view the articles citing this work by clicking on the number.


Find the Subject Headings!

Subject headings (aka subjects, subject terms, or descriptors) are ways that many databases and library catalogs categorize all items about a particular idea (not just items that mention an idea briefly). For example, you can search for the keyword sustainability (which could show up anywhere and only be briefly mentioned) or you can find a relevant item, look at the subject heading and click on the linked subject to find all the other materials that are all about that idea. You can also search again by subject headings. You'll probably find there's more than one subject heading that might apply to your topic and searching by these can make your search much more precise. For example, not only is sustainability a subject heading in the library catalog, but also sustainable development, natural resources management, etc.

Subject headings are like tags that collect all the books about a given subject, but they're standardized and assigned by librarians.

Check out the University of California Berkeley's tutorial on subject headings (it's for their library catalog, Melvyl, but the same techniques will work in our library catalog and in many of our databases).