CU Home Libraries Home Borrow Direct Ask Us
Search CLIO Help:
 About CLIO
Basic Search
     Title or Journal Title
     Subject Heading
     Call Number Browse
     Call Number Exact
     Uniform Title
     Author (grouped by title)
     Keyword (relevance ranked)
Guided Keyword
Course Reserves
Recent Acquisitions
Search History
Search all CU Catalogs
 Looking for... ?
Archives and Manuscripts
Conference Proceedings
Library Locations
Recent Acquisitions
Sound Recordings
Video Recordings
 Limiting Searches
Quick/More/Post Limits
Boolean Operators
 Search Results
Search Results Lists
CLIO Record Views
Library Locations
 Downloading Options
Using EndNote software
 Patron Empowerment
My Library Account
Renewing Borrowed Items
Saved Searches
 Request Materials
Recalls and Holds
Borrow Direct
Interlibrary Loan (ILL)
In Process/On Order
Item Search
 Connecting to CLIO
Using EndNote software
Using other Z39.50 clients

bullet Libraries Website Help

Boolean Operators

Using AND, OR, and NOT to Refine your Keyword Search

Boolean searching is based on an algebraic system of logic formulated by George Boole, a 19th century English mathematician. In a Boolean search, keywords are combined by the operators AND, OR and NOT to narrow or broaden the search (you do not have to enter them in capitals).

The operator AND narrows the search by instructing the search engine to search for all the records containing the first keyword, then for all the records containing the second keyword, and show only those records that contain both.
In CLIO, if you enter search terms without an operator, AND will automatically be inserted between them (but make sure that Javascript is enabled on your computer, or the search will fail).

The operator OR broadens the search to include records containing either keyword, or both.
The OR search is particularly useful when there are several common synonyms for a concept, or variant spellings of a word.


Bullet adolescent or teen?
Bullet medieval or "middle ages"
Bullet vergil or virgil

Combining search terms with the NOT operator narrows the search by excluding unwanted terms.

These Venn diagrams help to visualize the meaning of AND, OR and NOT; the colored area indicates the items that will be retrieved in each case.

moths AND butterflies

moths AND butterflies

You want to find books that are about both moths AND butterflies
moths OR butterflies

moths AND butterflies

You want to find books that are about moths, books that are about butterflies, and books that discuss both:
OR means MORE.
moths NOT butterflies

moths AND butterflies

You want to find books that are about moths, but EXCLUDE those that discuss butterflies

If you would like further assistance, Ask a Librarian for help.