Nowakowski, Andrzej, and Aleksandra Orpel. “Positive Solutions for a Nonconvex Elliptic Dirichlet Problem With Superlinear Response”. Topological Methods in Nonlinear Analysis 27, no. 1 (March 1, 2006): 177–194. Accessed March 29, 2024. https://apcz.umk.pl/TMNA/article/view/TMNA.2006.007.