Think broadly and abstractly!
Image from https://www.quora.com/What-makes-Boolean-Algebra-different-than-Binary-Code
Construct search by combining concepts with Boolean operators. Use keywords and subject terms in combination.
Boolean Logic Operators:
|AND||limits results, both concepts||stoma AND bowel cancer|
|OR||more results, either concept||stoma OR colostomy|
|NOT||excludes concept(s) from results||java NOT coffee|
Introduction to Boolean Logic tutorial