Hirata, Jun, Norihisa Ikoma, and Kazunaga Tanaka. “Nonlinear Scalar Field Equations in $\mathbb{R}^{N}$: Mountain Pass and Symmetric Mountain Pass Approaches”. Topological Methods in Nonlinear Analysis 35, no. 2 (April 23, 2010): 253–276. Accessed July 22, 2024. https://apcz.umk.pl/TMNA/article/view/TMNA.2010.015.