1. V. V. Dikarev, Astron. Astrophys. 346, 1011 (1999).
2. J. E. Howard, Phys. Lett. A 366, 91 (2007).
3. A. N. Starostin and Yu. V Petrushevich, Fiz. Plazmy 31(3), 233 (2005) [Plasma Phys. Rep. 31 (3), 206 (2005)].
4. A. E. Dubinov and M. A. Sazonkin, Zh. Tekh. Fiz. 78(9), 29 (2008) [Tech. Phys. 53, 1129 (2008)].
5. N. Meyer-Vernet, Astron. & Astrophys. 105, 98 (1982).