Mohd Tajuddin, A.R. , Rosdi Zakaria. “Discussion of Instructional Methods and Subjects by Caliph Harun ArRasyid (786-810AD) Educational Speech”. International Journal of Advanced Science and Technology 29, no. 7s (April 14, 2020): 398 - 402. Accessed September 23, 2021. https://sersc.org/journals/index.php/IJAST/article/view/9454.