1. Boriakoff, V., Buccheri, R. & Fauci, F. IAU Circ. No.3806 (1983).
2. Boriakoff, V., Buccheri, R. & Fauci, F. Nature 304, 417–419 (1983).
3. Backer, D. C., Kulkarni, S. R., Heiles, C., Davis, M. M. & Goss, W. M. IAU Circ. No.3743 (1982).
4. Backer, D. C., Kulkarni, S. R., Heiles, C., Davis, M. M. & Goss, W. M. Nature 300, 615 (1982).
5. Paczyński, B. Structure and Evolution of Close Binary Systems, IAU Symp. No. 88, 75 (1976).