Andres, Jan, and Karel Pastor. “On a Multivalued Version of the Sharkovskii Theorem and Its Application to Differential Inclusions, III”. Topological Methods in Nonlinear Analysis 22, no. 2 (December 1, 2003): 369–386. Accessed July 3, 2024. https://apcz.umk.pl/TMNA/article/view/TMNA.2003.046.