The averaging method of solving boundary-value problems for differential equation systems with slow and fast variables. Neliniini Kolyvannya, [S. l.], v. 1, n. 1, p. 51–65, 1998. Disponível em: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/9. Acesso em: 22 jan. 2026.