ARNOLD, V. I. On the topology of eigenfields. Topological Methods in Nonlinear Analysis, [S. l.], v. 26, n. 1, p. 9–16, 2005. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2005.022. Acesso em: 3 jul. 2024.