http://en.wikipedia.org/wiki/List_of_U.S._state_name_etymologies

Bright, William (2004). Native American Placenames of the United States. Norman: University of Oklahoma Press.

Guyton, Kathy (2009) U.S. State Names: The Stories of How Our States Were Named (Nederland, Colorado: Mountain Storm Press)

http://books.google.co.jp/books?id=83CIggbRi8YC&pg=PR14&dq=native+american+vocabulary&hl=ja&sa=X&ei=-Zm0T-fzEvGUiQftlaymAw&redir_esc=y#v=onepage&q=native%20american%20vocabulary&f=false

Native American Loanwords in American English Ginny Carney Wicazo Sa Review Vol. 12, No. 1 (Spring, 1997), pp. 189-203 

 Published by: University of Minnesota Press
 Article Stable URL: http://www.jstor.org/stable/1409169

http://books.google.co.jp/books?hl=ja&lr=&id=CfekuKBLfpIC&oi=fnd&pg=PR7&dq=native+american+loanwords+indian&ots=x3HnfnJghe&sig=dtOfPhPBwzObr0Kavp3oWlGQMf4#v=onepage&q=native%20american%20loanwords%20indian&f=false