Colgate University's Case Library has an extensive collection of American Indian literature and writings.Plenty of Everything and links to what they don't have. Inter-libra ray loans are possible on some materials.
Another fine collection of documents pertaining to American Indians. Many articles over one hundred years old. "The Navajo Indians "(1890) by Wm. Edwardy and "The Naming of the Indians" by Frank, Terry are among the more interesting. These are all scanned text that may be downloaded.