1. V. A. Magnitskii, The Internal Structure and Physics of the Earth (Nauka, Moscow, 1965) [in Russian].
2. L. M. Cathles, The Viscosity of the Earth’s Mantle (Univ. Press, Princeton, 1975).
3. R. J. Knops and E. W. Wilkes, in Handbuch der Physik (Springer Verlag, Berlin, 1973), Vol. 6a/3.
4. Yu. N. Rabotnov, Mechanics of Deformable Solids (Nauka, Moscow, 1979) [in Russian].
5. D. Bland, Theory of Linear Viscoelasticity (Pergamon Press, Oxford, New York, 1960).