Lopatin AK, Mitropolskiy YA. Bogolyubov averaging and normalization procedures in nonlinear mechanics. I. Ukr. Mat. Zhurn. [Internet]. 1994Sep.25 [cited 2024Nov.24];46(9):1171–1188. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/5634