EVTUKHOV, V. M.; SAMOILENKO, A. M. Conditions for the existence of solutions of real nonautonomous systems of quasilinear differential equations vanishing at a singular point. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 62, n. 1, p. 52–80, 2010. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2843. Acesso em: 5 dec. 2025.