SvistunO. P. “On Separatrix Curves of a Family of Linear Systems With Pulse Influence”. Ukrains’kyi Matematychnyi Zhurnal 45, no. 12 (December 25, 1993): 1682–1687. Accessed November 24, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5976.