ISBN 978-90-04-35621-4.CS1 maint: ref=harv (link) Kraemer, Joel L., ed. (1989). The History of al-Ṭabarī, Volume XXXIV: Incipient Decline: The Caliphates of al-Wāthiq, al-Mutawakkil and al-Muntaṣir, A.D. 841–863/A.H. 227–248.