When you are collecting information to perform a data analysis, Google commands are very useful...

If you include site: in your query, Google will restrict your search results to the site or domain you specify.

If you include filetype:suffix in your query, Google will restrict the results to pages whose names end in suffix. For example, [ web page evaluation checklist filetype:pdf ] will return Adobe Acrobat pdf files that match the terms “web,” “page,” “evaluation,” and “checklist.”

References: http://www.googleguide.com/advanced_operators_reference.html