Sverdan, M. L. “The Second Lyapunov Method for the Investigation of Stability of Differential Equations With Pulse Perturbations and Markov Coefficients”. Ukrains’kyi Matematychnyi Zhurnal, vol. 48, no. 6, June 1996, pp. 826-33, https://umj.imath.kiev.ua/index.php/umj/article/view/5282.