1. Newkirk, G., Jr. 1983, ARA&A, 21, 429
2. Willson, R. C., Hudson, H. S., Frohlich, C., & Brusa, R. W. 1986, Science, 234, 1114.
3. Grevesse, N. 1984, PhysScr, T8, 49
4. Grevesse, N., & Noels, A. 1993, in Origin and Evolution of the Elements, ed. N. Prantzos, E. Vangioni-Flam, & M. Casse (Cambridge: Cambridge University Press), p. 15.
5. Grevesse, N., & Sauval, A.J. 1998, SpSciRev, 85, 161.