1. Bidelman, W. P. 1953, Ap. J., 117, 25.
2. Bohannon, B. 1981, Bull. American Astron. Soc. 13, 526.
3. Bond, H. E., and Levato, H. 1976, Publ. Astron. Soc. Pacific
88, 905.
4. Dahari, O., and Osterbrock, D. E. 1984, Ap. J. 277, 648.
5. Darius, J., Gidding, J. R., and Wilson, R. 1979, The First Year of IUE, p. 36.