Vibration analysis of stress-driven nonlocal integral model of viscoelastic axially FG nanobeamsMahmood Fakher, Shahin Behdad and Shahrokh Hosseini-HashemiEur. Phys. J. Plus, 135 11 (2020) 905DOI: https://doi.org/10.1140/epjp/s13360-020-00923-6