Shchegolev, S. A. “On One Class of Solutions of a Countable Quasilinear System of Differential Equations With Slowly Varying Parameters”. Ukrains’kyi Matematychnyi Zhurnal 50, no. 8 (August 25, 1998): 1121–1128. Accessed April 26, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/4861.