Free Vibration Frequency of Thick FGM Spherical Shells Based on a Third-order Shear Deformation Theory. Eur. J. Pure Appl. Math. [Internet]. 2020 Oct. 31 [cited 2024 May 4];13(4):766-78. Available from: https://www.ejpam.com/index.php/ejpam/article/view/3826