YanchukS. V. “On the Behavior of Solutions of the Equation for Components of a Normal System of Differential Equations”. Ukrains’kyi Matematychnyi Zhurnal 49, no. 10 (October 25, 1997): 1436–1440. Accessed October 6, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5142.