Trapezon, K., and A. Trapezon. “Analytical Solution to the Problem about Free Oscillations of a Rigidly Clamped Circular Plate of Variable Thickness”. Eastern-European Journal of Enterprise Technologies, vol. 4, no. 7 (106), Aug. 2020, pp. 16-23, doi:10.15587/1729-4061.2020.201073.