@article{lien_duc_khiem_2017,  title={Free Vibration Analysis of Multiple Cracked Functionally Graded Timoshenko Beams},  volume={14},  ISSN={1679-7825},  url={https://doi.org/10.1590/1679-78253693},  DOI={10.1590/1679-78253693},  number={9},  journal={Latin American Journal of Solids and Structures},  publisher={Individual owner},  author={Lien, Tran Van and Duc, Ngo Trong and Khiem, Nguyen Tien},  year={2017},  month={Sep},  pages={1752–1766} }