1. A. Kh. Rakov and V. L. Rvachkov, ?The contact problem of the theory of elasticity for a half-space whose modulus of elasticity is a power function of the depth,? DAN URSR, no. 3, 1961.
2. I. Sneddon, ?Dual equations in elasticity,? Tr. mezhdunar. simpoziuma po prilizh. teorii funktsii v mekh. sploshnoi sredy, vol. 1, Nauka, Moscow, 1965.