FENSKE, C. C. A direct topological definition of the Fuller index for local semiflows. Topological Methods in Nonlinear Analysis, [S. l.], v. 21, n. 2, p. 195–209, 2003. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2003.012. Acesso em: 22 jan. 2022.