Try the site: operator
Try a Google search using site:edu (or site:.edu, whichever is easiest for you to remember).
You can change the domain to .gov, .org, .net, etc.
Example: site:org gangs
All search results are .org results, avoiding commercial and other websites. Narrowing your search in this manner is efficient.
Example search result
Why Young People Join Gangs - Los Angeles Police Department
Remember to carefully evaluate websites for accuracy, bias, etc. A librarian can assist with this.
More about URLs and Website Research
Website Research: URLs - Central Michigan University Libraries
Evaluating Internet Information - "dot com" "dot gov" — suffixes and country codes explained - University System of Georgia