Richard G. Hovannisian e Georges Sabagh, The Persian Presence in the Islamic World, Cambridge University Press, 1998, p. 7, ISBN 978-0-521-59185-0. URL consultato il 21 giugno 2013 (archiviato il 1º gennaio 2014).
«The Golden age of Islam [...] attributable, in no small measure, to the vital participation of Persian men of letters, philosophers, theologians, grammarians, mathematicians, musicians, astronomers, geographers, and physicians»
