NESTING
Nesting is a technique that allows you to organize complex statements using more than one kind of search operators. When you mix groups of keywords joined by different logical operators, it is often a good idea to group the sets together in the order you want the computer to process them. Otherwise, you may not get the result you expect. That grouping, known as “nesting,” is usually done with parentheses, although the individual boxes on advanced search screens serve the same purpose.
(czech OR polish) AND (drama OR theater OR theatre)