JANKOWSKI, T. Systems of Differential Inequalities with Initial Time Difference. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 56, n. 1, p. 139–145, 2004. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3737. Acesso em: 27 apr. 2025.