Hans Jansen: Mohammed (2005/7), German version: 2008 pp. 311-317; Fred Donner: Muhammad and the Believers - At the Origins of Islam (2012) pp. 73.
Hans Jansen: Mohammed (2005/7), German version: 2008 pp. 311—317; Fred Donner: Muhammad and the Believers — At the Origins of Islam (2012) pp. 73.