Passaseo, D. “The Effect of the Domain Shape on the Existence of Positive Solutions of the Equation $\Delta U + u^{2^*-1} = 0$”. Topological Methods in Nonlinear Analysis, vol. 3, no. 1, Mar. 1994, pp. 27-54, https://apcz.umk.pl/TMNA/article/view/TMNA.1994.002.