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

The World Atlas of Language Structures . (2005) · edited by Bernard Comrie and David Gil and Martin Haspelmath and Matthew S. Dryer · Oxford University Press

Language use in the Epena district of Northern Congo . William L. Gardner (1990) · http://www.sil.org/resources/publications/entry/9226

Babole ( pp. 190-210 ) . Leitch, Miles (1994) · In Typological Studies in Negation edited by Kahrel, Peter and Berg, René Van Den · John Benjamins

Les classes nominales et leur semantisme dans les langues bantu du nord-ouest ( pp. 169 ) . Idiata-Mayombo, Daniel Franck and Leitch, Myles Francis and Ondo-Mébiame, Pierre and Rekanga, Jean-Paul (2000) · Studies in African linguistics, #48 · Lincom Europa

Babole ( pp. 392-421 ch. 21 ) . Leitch, Myles (2003) · In The Bantu Languages edited by Nurse, Derek and Philippson, Gérard ·