Searches on the Open Web fail to capture many of the results from the so-called "deep web" (e.g., password-protected material or library catalog records). Moreover, search engines can often return irrelevant or non-scholarly results. Nonetheless, Google and other search engines can still be useful—if limited—discovery tools if you know how to refine your searches. For example, you might try limiting your search by various domains or using another one of the search tips offered here:
Limit your search by domain:
Search for synonyms:
Remove unwanted results:
Limit your search to words in the title:
Use the the Google Advanced Search screen to conduct advanced searches including, but not limited to, those above.
See Google's Cheat Sheet for further tips on constructing and refining your searches.
See Nancy Blachman's GoogleGuide for even more tips.