1. A. N. Tkachev and S. I. Yakovlenko, Pis’ma Zh. Éksp. Teor. Fiz. 77, 264 (2003) [JETP Lett. 77, 221 (2003)].
2. A. N. Tkachev, A. A. Fedenev, and S. I. Yakovlenko, Zh. Tekh. Fiz. 75(4), 60 (2005) [Tech. Phys. 50, 447 (2005)].
3. V. F. Tarasenko and S. I. Yakovlenko, Usp. Fiz. Nauk 174, 49 (2004) [Phys. Usp. 47, 887 (2004)].
4. A. N. Tkachev and S. I. Yakovlenko, Cent Eur. J. Phys. 2, 579 (2004); www.cesj.com/physics.html.
5. L. P. Babich, T. V. Loĭko, and V. A. Tsukerman, Usp. Fiz. Nauk 160, 49 (1990) [Sov. Phys. Usp. 33, 521 (1990)].