E. M. Parker, R. J. Hayward (1985) “ùrru”, in An Afar-English-French dictionary (with Grammatical Notes in English), University of London, →ISBN
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Marie-Claude Simeone-Senelle, Mohamed Hassan Kamil (2013 August) “Gender, Number and Agreement in Afar (Cushitic language)”, in 43th Colloquium on African Languages and Linguistics[2], Leiden: Leiden University