KorenevskyD. G. (1971) “On the averaging principle for hyperbolic second order equations with a functionally disturbed argument”, Ukrains’kyi Matematychnyi Zhurnal, 23(2), pp. 147-156. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/8497 (Accessed: 24November2024).