1. D. V. Otto, Radio Sci. 2, 1031 (1967).
2. E. K. N. Yung, Z. M. Xie, R. S. Chen, and Y. F. Han, Radio Sci. 34, 615 (1999).
3. A. S. Il’inskii, V. V. Kravtsov, and A. G. Sveshnikov, Mathematical Models of Electrodynamics (Vysshaya Shkola, Moscow, 1991) [in Russian].
4. Handbook of Numerical Analysis, Ed. by P. G. Ciarlet and J. L. Lions (Elsevier, 1991), Vol.2.
5. A. G. Sveshnikov and A. N. Bogolyubov, USSR Comput. Math. Math. Phys. 14 (4), 125 (1974).