Muayyad Mahmood Khalil. "On a Unique Solution of Fractional Differential System". Tikrit Journal of Pure Science 24, no. 3 (مايو 9, 2019): 128–132. تاريخ الوصول مايو 18, 2024. https://tjps.tu.edu.iq/index.php/tjps/article/view/381.