Tawliyah ra'is al-dawlah fi al-fikr al-siyasi al-Islami wa al-fikr al-siyasi al-hadith - Muhammad Khalil, Sa'd (al-Qahirah : al-Muassasah al-'Arabiyah al-Hadithah, 1988)
Thesis (Ph.D.)
Keywords: Presidents; Heads of state - islamic empire; Constitutional law (Islamic law).; Heads of state; Executive power (Islamic law).; Constitutional law; Islamic empire