Boolean search operators AND, OR, NOT, and SAME may be used to combine terms in order to broaden or narrow retrieval.

Case does not matter when using Booleans. For example, SAME, Same, and same returns the same results.

AND

Use AND to find records containing all terms separated by the operator.

SAME

Use SAME to find records where the terms separated by the operator appear in the same sentence. A sentence is defined as:

• the title of an article;
• a sentence in the abstract; or
• a single address.

Using the SAME operator instead of AND is a good way to narrow your search.

OR

Use OR to find records containing any of the terms separated by the operator.

NOT

Use NOT to exclude records containing certain words from your search.

Search Order Precedence

If you use different operators in your search, the search is processed according to this order of precedence:

1. SAME
2. NOT
3. AND
4. OR

copper OR lead AND algae finds all records in which both lead AND algae are present as well as all records in which the word copper is present.

(copper OR lead) AND algae finds all records in which the word algae is present together with either copper or lead.

Use of Parentheses

Use parentheses to override operator precedence. The expression inside the parentheses is executed first.

(cadmium AND gill*) NOT Pisces finds records containing both cadmium and gill (or gills), but excludes records containing the word Pisces

(honey bee* OR honeybee* OR Apis mellifera) SAME danc* find records containing any one of the words or phrases in parentheses (for example, honey bee, honey bees, honeybee, honeybees, Apis mellifera) in the same sentence as any word beginning with danc (for example, dance, dances, dancing).

AND Examples

Beverage AND bottle finds records containing both terms.

Beverage AND bottle AND beer finds records containing all three terms.

SAME Example

Beverage SAME bottle finds records in which these two terms must appear in the same sentence.

OR Example

Beverage OR bottle finds records containing either beverage or bottle (or both).

NOT Example

Beverage NOT bottle finds records containing beverage but excludes records containing bottle.