1. Becker, S.A. 1985, in Cepheids: Theory and Observations, ed. B.F. Madore (Cambridge: Cambridge University Press), p. 104.
2. Becker, S.A., Iben, I. and Tuggle, R.S. 1977, Ap. J. 218, 633.
3. Bohm-Vitense, E. 1986, Ap. J. 303, 262.
4. Bohm-vitense, E. and Proffitt, Ch. 1985, Ap. J. 296, 175.
5. Caccin, B., et. al. 1985, in Ce Neids: Theory and Observations, ed. B.F. Madore (Cambridge: Cambridge University Press), p. 43.