1. Cooper, J. E., Nature, 193, 744 (1962).
2. Abelson, P. H., and Parker, P. L., Carnegie Inst., Washington, Yearbook, 61, 181 (1962).
3. Cooper, J. E., and Bray, E. E., Geochim. Cosmochim. Acta, 27, 1113 (1963).
4. Bray, E. E., and Evans, E. D., Geochim. Cosmochim. Acta, 22, 2 (1961).
5. Bray, E. E., and Evans, E. D., Amer. Assoc. Petroleum Geol. Bull., 49, 248 (1965).