1. Breger, M., Garrido, R., Huang Lin, Jiang Shi-yang, Guo Zi-he, Frueh, M. and Pararó, M.: 1989,Astronomy and Astrophysics 214, 209.
2. Breger, M., McNamara, B. J., Kerschbaum, F., Huang Lin, Jiang Shi-yang, Guo Zi-he and Poretti, E.: 1990,Astronomy and Astrophysics 231, 56.
3. Kovács, G. and Pararó, M.: 1989,Monthly Notices of the RAS 237, 201.
4. Kurtz, D. W.: 1980,Monthly Notices of the RAS 193, 61.
5. Paparó, M. and Kovács, G.: 1984,Astrophysics and Space Science 105, 357.