RUIZ-HERRERA, A. Location of fixed points in the presence of two cycles. Topological Methods in Nonlinear Analysis, [S. l.], v. 38, n. 2, p. 407–420, 2011. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2011.040. Acesso em: 13 dec. 2024.