@article{bagheri_nikkar_ghaffarzadeh_2014,  title={Study of nonlinear vibration of Euler-Bernoulli beams by using analytical approximate techniques},  volume={11},  ISSN={1679-7825},  url={https://doi.org/10.1590/S1679-78252014000100010},  DOI={10.1590/S1679-78252014000100010},  number={1},  journal={Latin American Journal of Solids and Structures},  publisher={Individual owner},  author={Bagheri, S. and Nikkar, A. and Ghaffarzadeh, H.},  year={2014},  month={Jan},  pages={157–168} }