MARINO, A.; SACCON, C. Nabla theorems and multiple solutions for some noncooperative elliptic systems. Topological Methods in Nonlinear Analysis, [S. l.], v. 17, n. 2, p. 213–237, 2001. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2001.014. Acesso em: 26 apr. 2024.