Haykal, Muḥammad Ḥasanayn ; Aḥmad, Shaik̲h̲ Muḥammad 1927-1962 (1957) Abū Bakr : sīrat Ḥaẓrat Abū Bakr, Ṣiddīq-i Akbar. Maktabah-yi Jadīd. ISBN: .