1. N. P. Vekua, Systems of Singular Integral Equations [in Russian], Nauka, Moscow (1970).
2. R. G. Newton, J. Math. Phys.,23, 2257 (1982).
3. F. Gakhov, Boundary-Value Problems [in Russian], Nauka, Moscow (1977).
4. N. I. Muskhelishvili, Singular Integral Equations, Groningen (1953).
5. N. N. Bogolyubov, V. A. Meshcheryakov, and A. N. Tavkhelidze, in: Proc. Symposium on Continuum Mechanics and Problems of Analysis, Vol. 1 [in Russian], Institute of Mathematics, Georgian Academy of Sciences, Tbilisi (1973), pp. 5?14.