Guo, Zongming. “Structure of Large Positive Solutions of Some Semilinear Elliptic Problems Where the Nonlinearity Changes Sign”. Topological Methods in Nonlinear Analysis 18, no. 1 (September 1, 2001): 41–71. Accessed April 23, 2024. https://apcz.umk.pl/TMNA/article/view/TMNA.2001.023.