R.Y.S. Pak and B.B. Guzina (1995). “Three-dimensional wave propagation analysis of a smoothly heterogeneous solid”, J. Mech. Phys. Solids , 43, 533-551.

R.Y.S. Pak and B.B. Guzina (1995). “Three-dimensional wave propagation analysis of a smoothly heterogeneous solid”, J. Mech. Phys. Solids , 43, 533-551.  Article