GRAFF, G. Minimal number of periodic points for smooth self-maps of two-holed 3-dimensional closed ball. Topological Methods in Nonlinear Analysis, [S. l.], v. 33, n. 1, p. 121–130, 2009. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2009.009. Acesso em: 22 jul. 2024.