@article{rabelo_leonel_2008,  title={Finding invariant tori in the problem of a periodically corrugated waveguide},  volume={38},  ISSN={0103-9733},  url={https://doi.org/10.1590/S0103-97332008000100010},  DOI={10.1590/S0103-97332008000100010},  number={1},  journal={Brazilian Journal of Physics},  publisher={Sociedade Brasileira de Física},  author={Rabelo, Adriano Fábio and Leonel, Edson D.},  year={2008},  month={Mar},  pages={54–57} }