Mohammadimehr, M, et al. “Influence of the Elastic Foundation on the Free Vibration and Buckling of Thin-Walled Piezoelectric-Based FGM Cylindrical Shells Under Combined Loadings”. Journal of Solid Mechanics, vol. 6, no. 5, Dec. 2014, pp. 347-65, https://oiccpress.com/jsm/article/view/12473.