Samusenko, P.F. and ShkiI, N.I. (1996) “On asymptotic formulas for solutions of systems of linear differential equations with a degerate matrix with derivatives”, Ukrains’kyi Matematychnyi Zhurnal, 48(9), pp. 1278–1285. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/5241 (Accessed: 5 December 2025).