Fijalkowski, P., and B. Przeradzki. “On a Radial Positive Solution to a Nonlocal Elliptic Equation”. Topological Methods in Nonlinear Analysis, vol. 21, no. 2, June 2003, pp. 293-00, https://apcz.umk.pl/TMNA/article/view/TMNA.2003.017.