1. Benvenuti, P., Perinotto, M. 1981, this Conference.
2. Darius, J. et al. 1979, The First Year of IUE, Ed. A.J. Willis, p. 363
3. Darius, J. 1980, private communication
4. Iben, I., Truran, J.W. 1978, Astrophys. J. 220, 980
5. Iben, I. 1980, preprint