Searching the Web
After performing a Google search, select "quick settings" by selecting the cog button 
to get to the "advanced search." From there, limit to a specific domain, such as .gov, .edu, or .ucsb.edu. Additionally, you can limit by file type. Reports will typically be .pdf files.
You can also try the advanced search on Startpage for some high quality and ad-free results.
Evaulation Tools
Evaluating Web Pages - Cornell University
Evaluating Internet Sources - Georgetown University
Evaluate Your Sources - St. Louis Community College