Handbook of North American Indians
Two sets in paper:
-Baker-Berry Reference E77 .H25
-Baker-Berry Stacks E77 .H25
Aging, but extensive resource issued by the Smithsonian.
Available volumes include: Vol. 2: Indians in Contemporary Society ; Vol. 3: Environment, Origins, and Population ; Vol. 4: History of Indian-White relations ; Vol. 5: Arctic; Vol. 6: Subarctic; Vol. 7: Northwest Coast; Vol. 8: California; Vol. 9: Southwest; Vol. 10: Southwest; Vol. 11: Great Basin; Vol. 12: Plateau; Vol. 13: Plains; Vol. 14: Southeast; Vol. 15: Northeast; Vol. 17: Languages.
Some volumes are available online through the Internet Archive (see below)