1. L. M. Brekhovskikh, Waves in Layered Media (Akad. Nauk SSSR, Moscow, 1957), [In Russian].
2. G. A. Grachev, Akust. Zh. 29, 275 (1983).
3. I. V. Gindler and V. G. Petnikov, Akust. Zh. 33, 355 (1987).
4. A. N. Stepanov, Acoust. Phys. 42, 375 (1996).
5. A. N. Stepanov, Acoust. Phys. 42, 551 (1996).