1. Dopita, M. A, Lozinskaya, T., Mc Gregor, P.J., Rawling, S.J. 1990, ApJ 351, 563
2. Lortet, M.-C., Testor, G. 1991, A&A Suppl. 89, 185
3. Lozinskaya, T. 1991, in: K.A. van der Hucht& B. Hidayat B. (eds.), Wolf-Rayet Stars and Interrelations with Other Massive Stars in Galaxies, Proc. IAU Symp. No. 143 (Dordrecht: Kluwer), p. 371
4. Pakull, M.W. 1991, in: K.A. van der Hucht&B. Hidayat B. (eds.), Wolf-Rayet Stars and Interrelations with Other Massive Stars in Galaxies, Proc. IAU Symp. No. 143 (Dordrecht: Kluwer), p. 391
5. Polcaro, V.F., Viotti, R., Rossi, C., Norci, L. 1992, A&A 265, 563