Zgliczyński, Piotr. “Sharkovskii Theorem for Multidimensional Perturbations of One-Dimensional Maps II”. Topological Methods in Nonlinear Analysis 14, no. 1 (September 1, 1999): 169–182. Accessed July 3, 2024. https://apcz.umk.pl/TMNA/article/view/TMNA.1999.027.