^Zeki Hassan, John Esling, Scott Moisik, & lise Crevier-Buchman (2011) "Aryepiglottic trilled variants of /ʕ, ħ/ in Iraqi Arabic". Proceedings of the 17th International Congress of Phonetic Sciences (pp. 831–834), Hong Kong.
^Mr. Christfried Naumann, Doctoral Student, Department of Linguistics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany. June 26, 2009.