Siemaszko, Artur, and Jerzy Szymański. “On Exact Topological Flows”. Topological Methods in Nonlinear Analysis 21, no. 2 (June 1, 2003): 387–392. Accessed July 22, 2024. https://apcz.umk.pl/TMNA/article/view/TMNA.2003.024.