1. V. P. Maslov, Asymptotic Methods for Solution of Pseudodifferential Equations (Nauka, Moscow, 1987) [in Russian].
2. A. S. Mishchenko, B. Yu. Sternin, and V. E. Shatalov, Lagrangian Manifolds and Canonical Operator Method (Nauka, Moscow, 1976) [in Russian].
3. V. P. Maslov, Perturbation Theory and Asymptotic Methods (Mosk. Gos. Univ., Moscow, 1965) [in Russian].
4. M. Born and E. Wolf, Principles of Optics (Pergamon, Oxford, 1969; Nauka, Moscow 1970).
5. L. M. Brekhovskikh, Waves in Layered Media (Nauka, Moscow, 1973; Academic, New York, 1980).