Estimating the number of perturbed subharmonics in a system that is close to a Hamiltonian system and having one and a half degrees of freedom. Neliniini Kolyvannya, [S. l.], v. 14, n. 2, p. 147–180, 2011. Disponível em: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/598. Acesso em: 21 jan. 2026.