E. M. Parker, R. J. Hayward (1985) “ùsun”, inAn Afar-English-French dictionary (with Grammatical Notes in English), University of London,→ISBN
Mohamed Hassan Kamil (2004)Parlons Afar: Langue et Culture, L'Hammartan,→ISBN,page38
Mohamed Hassan Kamil (2015)L’afar: description grammaticale d’une langue couchitique (Djibouti, Erythrée et Ethiopie)[1], Paris: Université Sorbonne Paris Cité (doctoral thesis)