KUBICHKA, A. A.; PARASYUK, I. O. Bifurcation of a Whitney-Smooth Family of Coisotropic Invariant Tori of a Hamiltonian System under Small Deformations of a Symplectic Structure. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 53, n. 5, p. 610–624, 2001. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4284. Acesso em: 27 apr. 2025.