Wherry, Rev. E. M. (1882). A Comprehensive Commentary on the Quran comprising Sale's translation and Preliminary Discourse. Boston: Houghton, Mifflin and Company. σελ. 66.
Yarshater, Ehsan (1998). «The Persian presence in the Islamic world». Στο: Hovannisian, Richard G.· Sabagh, Georges, επιμ. The Persian Presence in the Islamic World. Cambridge, England: Cambridge University Press. σελίδες 4–125, page 28. ISBN978-0-521-59185-0.
Manfred, Albert Zakharovich, επιμ. (1974). A Short History of the World. 1. (translated into English by Katherine Judelson). Moscow: Progress Publishers. σελ. 182. OCLC1159025.