1. L. M. Brekhovskikh, Waves in Layered Media (Nauka, Moscow, 1973; Academic, New York, 1980).
2. M. Born and E. Wolf, Principles of Optics, 4th ed. (Pergamon, Oxford, 1969; Nauka, Moscow 1970).
3. A. A. Andronov, A. A. Vitt, and S. E. Khaikin, Theory of Oscillators (Fizmatgiz, Moscow, 1959; Pergamon Press, Oxford, 1966).
4. S. P. Strelkov, Introduction in Theory of Oscillations (Nauka, Moscow, 1964) [in Russian].
5. R. Z. Sagdeev, D. A. Usikov, and G. M. Zaslavsky, Nonlinear Physics: from the Pendulum to Turbulence and Chaos (Nauka, Moscow, 1988; Harwood Academic, New York, 1988).