@article {, title = {Aboriginal Trephining in Bolivia}, journal = {American Anthropologist}, volume = {6}, number = {4}, year = {1904}, note = {obsidian called chillisaa kala or "black flint", while "llisa" means "white flint". Obsidian, where available, was probably used trephining (p446). Also quotes Cobo on stomach operations using obsidian.}, pages = {440-446}, author = {Bandelier, Adolph F.} }