Samoilenko, A.M. (2002) “On the Asymptotic Integration of a System of Linear Differential Equations with a Small Parameter in the Coefficients of a Part of Derivatives”, Ukrains’kyi Matematychnyi Zhurnal, 54(11), pp. 1505–1517. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/4188 (Accessed: 6 December 2025).