After you've tried a search you can limit by selecting the Google gear

• then select Advanced search

• Scroll down to Narrow your results by and limit your search by producer type, select site or domain:
• .gov, for U.S. Government
• .ca.gov for California government
• .org, for non-profit organization
• .edu for a college or university in the United States
• .mil  for U.S. military server

You can also do this right in the search bar by typing site:

For example site:edu or site:ca.gov or