Meriam Library has a number of authoritative reference books and encyclopedias, shelved at the second floor Reference Collection. These Reference books will provide a broad outline of the subject and connect you to other sources.
Handbook of North American Indians by 
Native America in the Twentieth Century by 
Handbook of the Indians of California by 
Encyclopedia of North American Indians by 
Encyclopedia of Native Tribes of North America by 
Continuum Encyclopedia of Native Art by 
A Guide to the Indian Tribes of the Pacific Northwest by 
Encyclopedia of the American Indian Movement by 
Indigenous Peoples and Environmental Issues by 
Treaties with American Indians: an encyclopedia of rights, conflicts, and sovereignty by