1. I. P. Kulakov and A. V. Fadeev, Izv. Akad. Nauk SSSR, Neorg. Mater. 16(1), 159 (1980).
2. Acoustic Crystals (Nauka, Moscow, 1976).
3. B. M. Slepchenko, V. V. Musatov, and A. N. Bryzgalov, Fiz. Tverd. Tela (Leningrad) 32, 638 (1990) [Sov. Phys. Solid State 32, 375 (1990)].
4. A. N. Bryzgalov, Doctoral Dissertation (Ufa, 1998).
5. A. N. Bryzgalov, B. M. Slepchenko, and V. V. Musatov, Izv. Akad. Nauk SSSR, Neorg. Mater. 25, 1430 (1989).