SamoilenkoA. M. “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, no. 11 (November 25, 2002): 1505-1517. Accessed September 1, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/4188.