Hirano, Norimichi. “Multiplicity of Solutions for Nonhomogeneuous Nonlinear Elliptic Equations With Critical Exponents”. Topological Methods in Nonlinear Analysis 18, no. 2 (December 1, 2001): 269–281. Accessed April 19, 2024. https://apcz.umk.pl/TMNA/article/view/TMNA.2001.034.