Critical case of global stability of a nonautonomous essentially nonlinear system. Neliniini Kolyvannya, [S. l.], v. 3, n. 4, p. 449–457, 2000. Disponível em: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/137. Acesso em: 22 jan. 2026.