Volume 1
The Native Races
https://ia800203.us.archive.org/15/items/cihm_14152/cihm_14152.pdf
Volume 2
The Native Races
https://ia800907.us.archive.org/2/items/cihm_14153/cihm_14153.pdf
Volume 3
The Native Races
https://ia800304.us.archive.org/18/items/cihm_14154/cihm_14154.pdf
Volume 4
The Native Races
https://ia800208.us.archive.org/9/items/cihm_14155/cihm_14155.pdf
Volume 5
The Native Races
https://ia802604.us.archive.org/22/items/cihm_14156/cihm_14156.pdf
Many more available on archive.org website.
Have personally found up to volume 30+ on site.