D.B. Dhaigude, N.B. Jadhav, and J.A. Nanware. “Method of Upper Lower Solutions for Nonlinear System of Fractional Differential Equations and Applications”. Malaya Journal of Matematik 6, no. 03 (July 1, 2018): 467–472. Accessed July 16, 2024. https://www.malayajournal.org/index.php/mjm/article/view/821.