BUTRIS, R. N. Periodic Solution for Nonlinear System of Differential Equations Depending on The Gamma Distribution. Science Journal of University of Zakho, [S. l.], v. 2, n. 1, p. 204–212, 2014. Disponível em: https://sjuoz.uoz.edu.krd/index.php/sjuoz/article/view/164. Acesso em: 19 may. 2024.