BELARBI, Soumia, and Zoubir DAHMANI. “Solvability For a Nonlinear Coupled System of N Fractional Differential Equations”. MATEMATIKA: Malaysian Journal of Industrial and Applied Mathematics 30 (December 1, 2014): 123–133. Accessed September 28, 2021. https://matematika.utm.my/index.php/matematika/article/view/704.