Google Scholar indexes journal articles, books, abstracts, patents, and court opinions from universities, societies, publishers, online repositories, and other web sites to find scholarly information.
Google Scholar search results tend to be very large. There are several ways to refine a search and narrow results.
Clicking on the arrow at the right of the search box will take you to Google Scholar's Advanced Search.
Read Google's Advanced Scholar Search Tips.
Additional tips and information are available from the Google Scholar Blog, which is updated sporadically.