Saad, A., A. Elrokh, M. Mubarak, and S. Nada. “The Approximate Numerical Solutions to First Order Non-Linear Differential Equations and Their Connections to the Orthogonal Double Cover in Graph Theory”. Contemporary Mathematics, vol. 6, no. 4, June 2025, pp. 3873-89, doi:10.37256/cm.6420253740.