Sommer, Gabriele (1992) 'A survey on language death in Africa', in Brenzinger, Matthias (ed.) Language Death: Factual and Theoretical Explorations with Special Reference to East Africa.
Sommer, Gabriele (1992) 'An overview of language extinction in Africa', in Brenzinger, Matthias (ed.) Language Extinction: Research and Analysis with Special Reference to East Africa.