1. L. A. Vainshtein, Open Resonators and Open Waveguides [in Russian], Sov. Radio, Moscow (1970).
2. D. Marcuse, Theory of Dielectric Optical Waveguides, Academic Press (1974).
3. V. M. Babich and V. S. Buldyrev, Asymptotic Methods in Diffraction Problems for Short Waves [in Russian], Nauka, Moscow (1972).
4. V. M. Babich and N. Ya. Kirpichnikova, Method of Boundary Layer in Problems of Diffraction [in Russian], Leningrad State Univ. (1975).
5. V. M. Babich and T. F. Pankratova, in: Problems in Mathematical Physics [in Russian], Vol. 6, Leningrad State Univ. (1973), p. 9.