IGNAT'EV, A. O.; Konosevich В. I. On the stability of invariant sets of a system of autonomous differential equations under constantly acting perturbations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 51, n. 9, p. 1287–1291, 1999. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4725. Acesso em: 5 dec. 2025.