Chang, Shih-Sen, Yoel Je Cho, Xian Wu, and Ying Zhang. “The Topological Versions of KKM Theorem and Fan’s Matching Theorem With Applications”. Topological Methods in Nonlinear Analysis 1, no. 2 (June 1, 1993): 231–245. Accessed April 19, 2024. https://apcz.umk.pl/TMNA/article/view/TMNA.1993.017.