KHAFAGY, S. A. ON POSITIVE WEAK SOLUTIONS FOR A CLASS OF NONLINEAR SYSTEMS. Italian Journal of Pure and Applied Mathematics, [S. l.], v. 40, p. 149–156, 2018. Disponível em: https://journals.uniurb.it/index.php/ijpam/article/view/7045. Acesso em: 17 oct. 2026.