The library catalog and article databases such as Communication and Mass Media Complete are research tools that use search commands called Boolean Operators. These operators help the search engine to know how to locate the best results based on your query.
Most of this is built into the search interface, but this explanation may help you better manipulate your keywords when searching or to know what's going on when you search.
Most search engines recognize the use of Boolean Operators AND & OR.
Placing AND between keywords or phrases tells the search engine you'd like sources concerning an overlapping topic.
"I'd like to find articles about salary disparities and perceived impact within nonprofit organizations"
Inserting another AND between three or more keywords tells the search engine that you want a source that contains elements of each.
Adding OR to a statement tells the search engine that you'd accept a source pertaining to one of the keywords you used, but you'd also accept sources that refer to it in another way, containing an alternative term, or synonym. Synonyms can be really helpful here. Initially, the search engine would only give you articles containing "teen." When you tell it to also include articles that refer to this age group as "adolescent," you will double your results!
"I'll accept articles that use the phrasing "non profit" OR, I'll also accept articles that use the phrase "charity."