Perjalanan hidup empat khalifah rasul yang agung : Abu Bakar Ash-Shiddiq, Umar bin Al-Khaththab, Utsman bin Affan, Ali bin Abi Thalib - Al-HafizhIbnu Katsir (Jakarta Indonesia: Darul Haq, 2011)
Keywords: Caliphate -- History; Caliphs