I found an incredible site about native American history: http://www.firstpeople.us/. Check it out, there is a LOT of material.
Geronimo’s autobiography is there in its entirety. One interesting quote:
I have killed many Mexicans; I do not know how many, for frequently I did not count them. Some of them were not worth counting. It has been a long time since then, but still I have no love for the Mexicans. With me they were always treacherous and malicious.
—Geronimo, My Life: The Autobiography of Geronimo, 1905.
I knew he had issues with the United States, but I had not realized just how much he hated the Mexicans.