H. MAHMOOD, A.; اکرم; S. KARYAKOS, R.; رائد; H. SAADOON, L.; لمیاء. Solvability Conditions For A system Of Nonhomogenous Differntial Equations Of The First Order. Journal of Education and Science (JES), [S. l.], v. 21, n. 2, p. 150–154, 2008. DOI: 10.33899/edusj.2008.51253. Disponível em: https://rjps.uomosul.edu.iq/index.php/edusj/article/view/18404. Acesso em: 4 aug. 2025.