This link will take you to EBSCO's Academic Search Premier. Above the search boxes in the upper left corner, where it says "CHOOSE DATABASES" click and SELECT ALL databases. You CAN select full text and peer-reviewed. But if you want MORE results you should not limit to these.
This link will take you to Proquest's ABI/Inform database. In the upper left hand corner, where it says "searching 1 database" click and SELECT ALL the databases. The best results come when you then select peer-reviewed. But if you want MORE results, don't use that limit.
Searches many online encyclopedias at once. Type in Multicultural Encyclopedia and get results from The Multicultural Encyclopedia of America. Then, in search box on left, type in keyword, such as Tonga , to go to relevant results.