Enad, W. F. “The Emirate of Hajj During the Reign of Caliph Harun Al-Rashid (170-193 AH/786-808 AD)”. Journal of Tikrit University for Humanities, vol. 29, no. 8, 1, Aug. 2022, pp. 137-56, doi:10.25130/jtuh.29.8.1.2022.07.