You can combine search terms using the Boolean operators AND, OR, or AND NOT. If you enter two or more terms into a search field and do not enclose the terms in quotation marks, they will automatically be combined with AND. For example,
female history
and
female AND history
will retrieve the same documents.

To combine search terms using Boolean operators, type the terms you wish to search for and separate them with the appropriate term.

The AND operator retrieves all items which contain both of the terms it separates. Using AND reduces the number of documents you retrieve. For example,
health AND welfare
will retrieve documents containing the term 'health' and the term 'welfare'.

The OR operator retrieves all items which contain either or both of the terms it separates. Using OR increases the number of documents you retrieve. For example,
obstetrics OR gynecology
will retrieve documents containing either 'obstetrics' or 'gynecology' (or both).

The AND NOT operator retrieves all items which contain the first term but not the second. For example,
suffrage AND NOT temperance
will retrieve all documents containing 'suffrage' that do not contain the term 'temperance'.

Note: Boolean operators can be typed in either upper case letters (e.g. 'AND') or lower case letters (e.g. 'and').