Marchi, E., and J.-E. Martínez-Legaz. “A Generalization of Fan-Browder’s Fixed Point Theorem and Its Applications”. Topological Methods in Nonlinear Analysis, vol. 2, no. 2, Dec. 1993, pp. 277-91, https://apcz.umk.pl/TMNA/article/view/TMNA.1993.043.