Frye 1949, p.585. Frye, Richard N. (1949). «Reviews: P.K. Hitti, History of the Arabs». Speculum. 24 (4): 582–587. doi:10.2307/2854655
Goitein 1964, p.118. Goitein, S.D. (1964). «The Commercial Mail Service in Medieval Islam». Journal of the American Oriental Society. 84 (2): 118–123. doi:10.2307/597098
Goitein 1964, p.119. Goitein, S.D. (1964). «The Commercial Mail Service in Medieval Islam». Journal of the American Oriental Society. 84 (2): 118–123. doi:10.2307/597098
Goitein 1964, p.118-19. Goitein, S.D. (1964). «The Commercial Mail Service in Medieval Islam». Journal of the American Oriental Society. 84 (2): 118–123. doi:10.2307/597098