al-Hādī, Ibn al-Jawzī, Abū al-Faraj ʻAbd al-Raḥmān ibn ʻAlī, approximately 1116-1201 ; Ḥusayn, Ḥasan. Taʼrīkh ʻUmar ibn al-Khaṭṭāb : awwal ḥākim dīmūqrāṭī fī al-islām. Maktabah al-Jadīdah, 1935.