Omer, E. M. “THE ATA SYSTEM: ITS ORIGIN, DEVELOPMENT AND SOCIO-ECONOMIC IMPACT ON THE SOCIETY OF MEDINA DURING THE ERAS OF THE RIGHTLY GUIDED CALIPHS (11-40AH/632-661AD)”. Journal of Al-Tamaddun, vol. 15, no. 1, May 2020, pp. 109-17, doi:10.22452/JAT.vol15no1.7.