BAZHURA, B. P.; SAMOILENKO, A. M. Investigation of a dynamical system in a neighborhood of an invariant toroidal manifold in the general case. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 46, n. 10, p. 1399–1408, 1994. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5620. Acesso em: 17 apr. 2025.