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) ·

Endangered Languages in Central Africa ( pp. 163-178 ) . Bruce Connell (2007) · In Language Diversity Endangered edited by Matthias Brenzinger · Mouton de Gruyter

Atlas of the World’s Languages in Danger . Christopher Moseley (ed.) (2010) · UNESCO Publishing http://www.unesco.org/culture/en/endangeredlanguages/atlas

An Atlas of Nigerian Languages . Roger Blench (2011) · Mallam Dendo http://www.rogerblench.info/Language/Africa/Nigeria/Atlas%%20of%%20Nigerian%%20Languages-%%20ed%%20III.pdf

Amasi, Ambele und Asumbo -- klassensprachen aus dem Nordlichen Westkamerun ('Mamfe'-Bantu) ( pp. 56-67, 30-42 ) . H. Jungraithmayr and Angelika von Funck (1975) · Africana Marburgensia. 8 (1, 2) ·