Gabriel Horn looks pretty questionable. We need to a start a research thread on him.
http://www.ipl.org/div/natam/bin/browse.pl/A292Dream Catchers actually looks like it'd be quite a good book. I'm going to look for it myself. Look at the description.
"How attitudes toward Native American spiritually evolved from horror to appropriation."
The Judith Nies book is pretty good. I have it.
I haven't read the Hirschfelder book, but I know she does some very good work.
The Black Kettle book looks like straightforward history, but I haven't read it either.