LukovskyI. O. 2018. “Variational Method for the Solution of Nonlinear Boundary-Value Problems of the dynamics of Bounded Volumes of Liquid With Variable Boundaries”. Ukrains’kyi Matematychnyi Zhurnal 70 (1), 63-78. http://umj.imath.kiev.ua/index.php/umj/article/view/1542.