Al-Hayani, Waleed, and Mohammed J. Ahmed. “The Homotopy Perturbation Method to Solve Initial Value Problems of First Order With Discontinuities”. AL-Rafidain Journal of Computer Sciences and Mathematics 16, no. 2 (December 5, 2022): 61–70. Accessed October 13, 2025. https://csmj.uomosul.edu.iq/index.php/csmj/article/view/36860.