I've got a project to do on witchcraft or sorcery for my anthropology class, and I chose to do sumu because I've heard of this type of magic when discussing Dian Fossey...I haven't even found out if it was a particular tribe/group that practiced this sort of witchcraft or if it was widespread across Rwanda.
However, I've searched on Yahoo and Google for good, reliable sources on this topic and I've come up short. I was wondering if anyone could offer help. :]
I can't find a thing on Amazon, the entire Chicago public library database...or my university's Illinois shared library database (includes 70 schools' books). I even tried an article search and nothing specific came up. I suggest you swing to Haiti topics or broaden your discussion of black magic beyond "sumu", it's not coming up in any of my searches.
Try a book called,
Witchcraft and Magic Among the Azande. By E.E. Pritchard.
It's a staple anthropological text and discusses a form of magic/witchcraft called Mangu practiced by a group living in the Sudan. Theres a ton of material on it too so you should be more productive in your search.