Endangered Languages Catalogue Project. Compiled by research teams at University of Hawai'i Mānoa and Institute for Language Information and Technology (LINGUIST List) at Eastern Michigan University . (2012) ·

Ethnologue: Languages of the World, 16th Edition (2009) . (2009) · edited by M. Paul Lewis · SIL International http://www.ethnologue.com/

A survey on language death in Africa ( pp. 402 ) . Sommer, Gabriele (1992) · In Language death: factual and theoretical explorations with special reference to East Africa Contributions to the sociology of language, #64 · edited by Brenzinger, Matthias · Mouton de Gruyter

An Atlas of Nigerian Languages ( pp. 111 ) . Roger Blench (2012) · http://www.rogerblench.info/Language/Africa/Nigeria/Atlas%20of%20Nigerian%20Languages-%20ed%20III.pdf