You would follow your subject with a subdivision for those types of materials. You could find statistics, or a subject limited to a certain geographical area by using subdivisions. Now that you know what words you want to use, you are ready to search. You will then get a screen where there are two columns. You will then be prompted for your term.
Different databases use different ways of listing subjects.
These are online as well as in print. You can bring up a thesaurus simply by clicking on the Thesaurus button at the top of the screen. This will take you to a new screen where there will be a line for you to type in your term. If your term does not appear, think of variations for the term and repeat the process until you find a matching term. You will be returned to the search screen and the results of the new term will appear.