1. K. Warner and J. R. Beamish, Phys. Rev. B 50, 15896 (1994).
2. A. V. Gartvik, Candidate’s Dissertation in Physics and Mathematics (St. Petersburg, 2005).
3. B. F. Borisov, A. V. Gartvik, A. G. Gorchakov, et al., in Proceedings of XVI Session of the Russian Acoustical Society (GEOS, Moscow, 2005), Vol. 1, p. 12.
4. B. F. Borisov, A. V. Gartvik, F. V. Nikulin, and E. V. Charnaya, Akust. Zh. 52, 172 (2006) [Acoust. Phys. 52, 138 (2006)].
5. B. F. Borisov, A. V. Gartvik, Yu. A. Kumzerov, et al., in Proceedings of XV Session of the Russian Acoustical Society (GEOS, Moscow, 2004), Vol. 1, p. 140.