1. Arnold, J. R. (1964), in: H. Craig, S. L. Miller, and G. J. Wasserburg (eds.), Isotopic and Cosmic Chemistry, North-Holland Publishing Co., Amsterdam.
2. Bottema, M., Plummer, W., and Strong, J. (1964), Astrophys. J. 139: 1021.
3. Brown, H. (1952), in: G. P. Kuiper (ed.), The Atmospheres of the Earth and Planets, University of Chicago Press, Chicago.
4. Cameron, A. G. W. (1962), Icarus
1: 13.
5. Cameron, A. G. W. (1963a), in: R. Jastrow and A. G. W. Cameron (eds.), Origin of the Solar System, Academic Press Inc., New York.