“The Cauchy Problem for a System of Linear Inhomogeneous Differential Equations of the First Order With a Degenerate Matrix at Derivatives and the Pulse Action at Fixed Instants of Time”. Neliniini Kolyvannya 25, no. 4 (December 29, 2022): 325–340. Accessed April 11, 2026. https://nosc.imath.kiev.ua/index.php/nosc/article/view/1076.