Martynyuk, A. A., and I. P. Stavroulakis. 1999. “Stability Analysis With Respect to Two Measures of Impulsive Systems under Structural Perturbations”. Ukrains’kyi Matematychnyi Zhurnal 51 (11): 1476–1484. https://umj.imath.kiev.ua/index.php/umj/article/view/4749.