Andres, J., and K. Pastor. “On a Multivalued Version of the Sharkovskii Theorem and Its Application to Differential Inclusions, III”. Topological Methods in Nonlinear Analysis, vol. 22, no. 2, Dec. 2003, pp. 369-86, https://apcz.umk.pl/TMNA/article/view/TMNA.2003.046.