Svistun, O.P. (1993) “On separatrix curves of a family of linear systems with pulse influence”, Ukrains’kyi Matematychnyi Zhurnal, 45(12), pp. 1682–1687. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/5976 (Accessed: 5 December 2025).