Robert D. Burrowes, Historical Dictionary of Yemen, Scarecrow Press, 2010, art. "Anglo-Ottoman line of 1904", p. 30-31 [1]
(en) Europa Publications Staff, Europa Publications Staff Europa Publications, The Middle East and North Africa 2003, Londres, Routledge, , 49e éd., 1286 p. (ISBN978-1-85743-132-2, lire en ligne), p. 1205