1. Sneddon, I. N.,Mixed Boundary Value Problems in Potential Theory, North-Holland, 1966.
2. Sneddon, I. N., and Lowengrub, M.,Crack Problems in the Theory of Elasticity, Wiley 1969.
3. Sparenberg, J. A.,Appl. Sci. Res. 7A, 1958, p. 109.
4. Spillers, W. R.,J. Math. Phys. 43, 1964, p. 65.
5. Yau, W. W. F. and Cakmak, A. S.,Int. J. Engng. Sci., 4, 1966, p. 463.