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/

World Oral Literature Project . http://www.oralliterature.org

Étude Sociolinguistique De La Langue zirenkel Du Tchad . Eric Johnson (2005) · SIL http://www.sil.org/silesr/2005/silesr2005-023.pdf

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