1. A. Herrero, R. P. Kudritzki, R. Gabler, et al., Astron. Astrophys. 297, 556 (1995).
2. I. B. Voloshina, V. M. Lyutyi, and A. E. Tarasov, Pis'ma Astron. Zh. 23, 335 (1997) [Astron. Lett. 23, 293 (1997)].
3. E. A. Karitskaya, V. P. Goranskii, K. N. Grankin, and S. Yu. Mel'nikov, Pis'ma Astron. Zh. 26, 27 (2000) [Astron. Lett. 26, 22 (2000)].
4. C. Brocksopp, R. P. Fender, V. M. Larionov, et al., Mon. Not. R. Astron. Soc. 309, 1063 (1999).
5. V. G. Kornilov and A. V. Krylov, Astron. Zh. 70, 426 (1993) [Astron. Rep. 37, 221 (1993)].