O. P. Svistun, “On separatrix curves of a family of linear systems with pulse influence”, Ukr. Mat. Zhurn., vol. 45, no. 12, pp. 1682–1687, Dec. 1993, Accessed: Feb. 17, 2026. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/5976