For further reading about the Nez Perce and history surrounding the novel, I recommend the following books:

To purchase, click on the book title:

History of the Nez PerceThe Nez Perce Indians and the Opening of the Northwest by Alvin M. Josephy, Jr.

The Nez Perce and Lewis & ClarkLewis & Clark Among the Nez Perce: Strangers in the Land of the Nimiipuu by Allen V. Pinkham

The 1877 War

Nez Perce lands and the Nez Perce trail:

The Nez Perce and missionaries:  

For Children: Kaya, An American Girl: 1764/Box Set by Janet Beeler Shaw