Sharif, Abdulrahman A., and Ahmed A. Hamoud. “On $\psi$-Caputo Fractional Nonlinear Volterra-Fredholm Integro-Differential Equations”. Discontinuity, Nonlinearity, and Complexity 11, no. 1 (March 1, 2022): 97–106. Accessed October 17, 2026. https://lhscientificpublishing.com/index.php/DNC/article/view/2083.