Gristchak, V. Z., and V. N. Kabak. 2019. “Double Asymptotic Method for Nonlinear Forced Oscillations Problem of Mechanical Systems With Time Dependent Parameters”. Technische Mechanik - European Journal of Engineering Mechanics 16 (4):285-96. https://journals.ub.ovgu.de/index.php/techmech/article/view/1246.