PERERA, K.; AGARWAL, R. P.; O’REGAN, D. Nontrivial solutions of $p$-superlinear anisotropic $p$-Laplacian systems via Morse theory. Topological Methods in Nonlinear Analysis, [S. l.], v. 35, n. 2, p. 367–378, 2010. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2010.021. Acesso em: 3 jul. 2024.