1. Introduction

2. Why use the Library?

3. Library Password

4. Boolean Searching

5. Library Catalog
  • How to Find Books
  • How to Find Journals

6. Databases
  • Search for Articles
  • Find Articles

7. Organizations

8. How to Get Help

9. Library Exercise

10. PLS 101A Resources

4. Boolean Searching

Boolean searching is a feature available in most of our databases and in the Library Catalog. Using Boolean Operators can make your search more focused and effective. The basic Boolean Operators are AND, OR, NOT.

In the venn diagrams below, the shaded parts represent the materials that are retrieved.

The AND operator

When you use AND between two or more keywords, you're asking for results that include all keywords. This is a good way to narrow your search, to cut down on a large number of results, and to focus your search.

For example :

foreign policy and united states
housing discrimination and supreme court
voting and polls and Iowa

The OR operator

When you use OR between keywords, you're asking for results that include any of the keywords. This is a good way to increase the number of results and enlarge your search. You can also use OR to allow for alternative spellings and the use of acronyms or synonyms.

For example:

defense or defence
American Political Science Association or APSA
judicial or legislative

The NOT operator

When you use the NOT operator, you're asking for results that exclude one of the keywords. This is another way to cut down on the number of results and focus your search. Some databases will not accept a NOT search. When it is available, use NOT with caution as you might inadvertently exclude useful search results.

For example:

court not supreme
presidents not Lincoln
Mexico not new

Boolean Operators in Databases

Boolean operators are often available on database search pages. Look for pulldowns with Boolean operators. You can also type your search terms using Boolean operators. For example:

Check the database's "Help" or "Information" pages for details about using Boolean operators in that database.

Truncation

Many databases also support truncation -- the use of a character at the end of a word stem to search all words that begin with that word stem. Truncation is equivalent to using the or operator.

For example:

• politic* will retrieve political or politics or politicize...
• elect* will retrieve elect or elected or electing or elections...

* or ? or + are frequently used as truncation symbols or wildcard characters. The database's "Help" or "Information" screens will tell you which character(s) to use.

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