Aleomraninejad, S. M. A., S. Rezapour, and N. Shahzad. “Fixed Points of Hemi-Convex Multifunctions”. Topological Methods in Nonlinear Analysis, vol. 37, no. 2, Apr. 2011, pp. 383-9, https://apcz.umk.pl/TMNA/article/view/TMNA.2011.020.