The Muskogee Co. Library's Genealogy section has the Soundex for 1900 Chickasaw and I believe the Choctaw Nations, along with the censuses for them. I don't remember if they have one for the Creek Nation or not. They also have most of the Daily Oklahoman, and the Muskogee Daily Phoneix(spelling!) there too. There is also an 1890 Oklahoma Territorial census,(Oklahoma Territory only, no Indian Territory). Hope this helps.