SAMOILENKO, A. M. On some problems in perturbation theory of smooth invariant tori of dynamical systems. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 46, n. 12, p. 1665–1699, 1994. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5577. Acesso em: 5 dec. 2025.