LUCHKA, A. Y. Methods for the investigation of systems of differential equations with pulse influence. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 50, n. 2, p. 189–194, 1998. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4954. Acesso em: 5 dec. 2025.