Constructing a search using parentheses
Use parentheses for clarity in your search statement.
Enclose words connected with OR in parentheses -- especially if you're using AND in the same search.
For example, the following search will find items about fleas in either cats or dogs: fleas and (cats or dogs)
Here's what is looks like on PubMed. Note the differing results and meaning based on how you use the parentheses:
