Ding, Boyang, and Changming Ding. “Poincaré Recurrence Theorem in Impulsive Systems”. Topological Methods in Nonlinear Analysis 49, no. 2 (January 11, 2017): 577–585. Accessed July 27, 2024. https://apcz.umk.pl/TMNA/article/view/TMNA.2016.091.