... (1951) 316. Mindlin R.D. Vibrations of an infinite elastic plate and its cut-off frequencies, Proc Third US Nat. Congr. Appl. Mech., (1958) 225. Mindlin R.D. Waves and vibrations in isotropic, ... Waves in Fluids and Solids 66Gogoladze V.G. Dispersion of Rayleigh Waves in a Layer (in Russian), Publ. Inst. Seism. Acad. Sci. U.R.S.S. 119 (1947) 27 – 38. Graff K. F. Wave Motion in ... for surface waves in layers with varying thickness, J. Math. Anal. Appl. 21 (1968) 431 – 441. Waves in Fluids and Solids 64Proof a) flows out from considering the right-hand-side of (6.1),...