LÓPEZ-GÓMEZ, Julian; MORA-CORRAL, Carlos. Counting solutions of nonlinear abstract equations. Topological Methods in Nonlinear Analysis, [S. l.], v. 24, n. 2, p. 307–335, 2004. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2004.030. Acesso em: 8 jul. 2025.