A comprehensive search for literature on your topic will require searching more than one database and using more than one search technique. The Library Quick Search on the library's home page is a good place to start, but for more sources you will want to use subject-specific databases that contain materials from the major journals and publications in a given field.
Look for your subject's Research Guide for a list of the databases most relevant to your research topic here: http://libguides.sdstate.edu/az.php
A controlled vocabulary is a list of standard terminology that
Databases use different terms to refer to controlled vocabulary. The most common are subjects, subject terms, headings, subject headings, and descriptors.
There are two ways to find the preferred terms for your topic and include them in your search:
The following video demonstrated both techniques.
Researchers typically cite the work of many others. You can use these lists of references to find more sources on your topic.
You can also follow the citation trail forward to find more recent studies that cite one you are looking at.
Changing your Google Scholar settings could save you a lot of time.