Sokil, B. I. (1997) “On asymptotic approximation of a solution of a boundary-value problem for a nonlinear nonautonomous equation”, Ukrains’kyi Matematychnyi Zhurnal, 49(11), pp. 1580–1583. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/5160 (Accessed: 22May2024).