In the example above, looking for articles on the differences among races with regard to exercise patterns, there were two simple searches, one focusing on race and the other focusing on exercise. It creates one big set by combining all the sets. Note the difference between the two. The first represents the practice itself while the second refers to the practitioners. In terms of searching, they can be seen as synonymous and combined by advanced nursing practice or advanced practice nurses .
Some online resources allow additional operators.
Some allow combining by set numbers and some do not. Some have a guided technique for combining, and others allow the combining command to be typed in directly. To determine the type of combining that can be done in a particular source, consult the source's online help. Limiting Searches Using the AND operator is one way to narrow a search. For information on limiting in a particular resource, consult that resource's online help.