PETRUS, R.; YOUNIS, A. The existence and convergence of the solution to a system of non-linear integral-differential equations of the first rank with the requirements of integration. Journal of Education and Science, [S. l.], v. 18, n. 1, p. 138–151, 2006. DOI: 10.33899/edusj.2006.78712. Disponível em: https://ojs.uomosul.edu.iq/index.php/edusj/article/view/41532. Acesso em: 7 sep. 2025.