VITRYCHENKO, I. E. Functional polystability of some nonautonomous quasilinear differential systems. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 51, n. 7, p. 989–995, 1999. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4688. Acesso em: 5 dec. 2025.