Ignat’ev AO. On the existence of a lyapunov function as a quadratic form for impulsive systems of linear differential equations. Ukr. Mat. Zhurn. [Internet]. 2010Nov.25 [cited 2024May7];62(11):1451–1458. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/2970