The Boolean operators (named after 19th-century logician George Boole) are AND, OR, and NOT.
|cat AND dog||This retrieves items that have the word cat and the word dog.|
|cat OR dog||This retrieves items that have the word cat or the word dog.|
|cat NOT dog||This retrieves items that have the word cat but not the word dog. Use this with caution.|
Boolean operators can be grouped with parentheses:
(cat OR feline) AND (dog OR canine)
Note: Most search engines do not require that Boolean operators be written in capital letters. However, a few do. If in doubt, capitalize.
Truncation is used to retrieve items having various forms of words. It is especially useful for finding singular and plural forms of nouns.
In most database search engines, the truncation symbol is the asterisk ( * ).
In the U of R library catalogue, the truncation symbol is the question mark ( ? ).
accelerat* This retrieves items that have accelerate, accelerates, accelerating, acceleration, acceleratory, accelerative, etc.
Phrases are sequences of words that appear together in the order specified. Use quotation marks to indicate phrases.
"uncertainty principle" This retrieves items having this phrase, but not items in which uncertainty appears somewhere and principle appears somewhere else, but not next to each other in that order.