Lopatin AK, Mitropolskiy YA. Bogolyubov averaging and normalization procedures in nonlinear mechanics. II. Ukr. Mat. Zhurn. [Internet]. 1994Nov.25 [cited 2024Sep.1];46(11):1509–1526. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/5590