MASSA, E.; RUF, B. On the Fučík spectrum for elliptic systems. Topological Methods in Nonlinear Analysis, [S. l.], v. 27, n. 2, p. 195–228, 2006. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2006.008. Acesso em: 17 apr. 2024.