HIRATA, J.; IKOMA, N.; TANAKA, K. Nonlinear scalar field equations in $\mathbb{R}^{N}$: mountain pass and symmetric mountain pass approaches. Topological Methods in Nonlinear Analysis, [S. l.], v. 35, n. 2, p. 253–276, 2010. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2010.015. Acesso em: 22 jul. 2024.