Aizicovici, Sergiu, Nikolaos S. Papageorgiou, and Vasile Staicu. “Existence and Multiplicity of Solutions for Resonant Nonlinear Neumann Problems”. Topological Methods in Nonlinear Analysis 35, no. 2 (April 23, 2010): 235–252. Accessed December 13, 2024. https://apcz.umk.pl/TMNA/article/view/TMNA.2010.014.