Ignat’ev, A. O., and R. I. Gladilina. 2003. “On Necessary and Sufficient Conditions for the Asymptotic Stability of Impulsive Systems”. Ukrains’kyi Matematychnyi Zhurnal 55 (8), 1035-43. https://umj.imath.kiev.ua/index.php/umj/article/view/3979.