STEP 1:
Begin by clicking on the link to "Settings”
STEP 2:
Then, click on the link to select "Advanced Search”
STEP 3:
Through the "Advanced Search” form you have the ability to limit your search to government, non-governmental organizations (NGOs) and educational sites
Under the "Narrow your results" tab, in the "site or domain" field enter:
.gov (for government websites)
.org (for non-governmental organization websites)
.edu (for educational websites)