Furtado, Marcelo F. “Nodal Solutions for a Nonhomogeneous Elliptic Equation With Symmetry”. Topological Methods in Nonlinear Analysis 29, no. 1 (March 1, 2007): 69–78. Accessed April 18, 2024. https://apcz.umk.pl/TMNA/article/view/TMNA.2007.004.