Figueroa, Rubén, Rodrigo López Pouso, and Jorge Rodríguez-López. 2018. “A Version of Krasnosel’skiĭ’s Compression-Expansion Fixed Point Theorem in Cones for Discontinuous Operators With Applications”. Topological Methods in Nonlinear Analysis 51 (2):493-510. https://apcz.umk.pl/TMNA/article/view/TMNA.2018.003.