Key Ideas > Truncation > Phrases > Boolean Logic > Subjects/Descriptors > Review and Refine > Limiting > Citation Indexes

Boolean Logic allows keywords and phrases to be combined in a logical way using operators. The most important operators are AND and OR.

• AND
  • Use for unrelated ideas
    eg "sustainable development" and oceans
• OR
  • Use for the same idea expressed in different ways
    eg oceans or seas or coast*
• ( )
  • If you are using AND and OR in the same search statement, it is important to use parentheses to 'nest' the search terms
  • Put ( ) around the OR keywords
    eg "sustainable development" and (oceans or seas or coast*)

Note the use of the previous techniques along with Boolean Logic: key ideas, truncation and phrases.

• Quick guide to search operators in selected databases

[More about Boolean Logic... | More about Nesting...]