FONDA, A. Topological degree and generalized asymmetric oscillators. Topological Methods in Nonlinear Analysis, [S. l.], v. 28, n. 1, p. 171–188, 2006. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2006.026. Acesso em: 3 jul. 2024.