Abdullah, S., and N. Mohd Talib. “The Decline of the Umayyad Caliphate in Andalus Based on Ibn Khaldun’s Theory”. Journal of Al-Tamaddun, vol. 18, no. 2, Dec. 2023, pp. 39-51, https://jml.um.edu.my/index.php/JAT/article/view/32464.