Cardona, Jorge E., and Lev Kapitanski. “Semiflow Selection and Markov Selection Theorems”. Topological Methods in Nonlinear Analysis 56, no. 1 (September 5, 2020): 197–227. Accessed July 22, 2024. https://apcz.umk.pl/TMNA/article/view/TMNA.2020.010.