%0 Journal Article
%J American Anthropologist
%D 1904
%T Aboriginal Trephining in Bolivia
%A Bandelier, Adolph F.
%P 440-446
%V 6
%Z 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.