To search for more than one term at a time, you must use Boolean operators.
The two mostly commonly used operators are AND and OR.
To combine multiple concepts in a single search, use brackets to group concepts together. For example, search for headache AND (aspirin OR acetaminophen), not headache AND aspirin OR acetaminophen
To build a search with various concepts using Boolean Operators, click on the Advanced Search link at the top of the page.
Step 1: Type keywords (one concept at a time)
Step 2: Click ADD
Step 3: Repeat Steps 1 & 2 for each concept
Step 4: Click Search