1. Paneth, F. A., et al., Geochim. et Cosmochim. Acta, 3, 257 (1953).
2. Bauer, C. A., Phys. Rev., 74, 225, 501 (1948).
3. Huntley, H. E., Nature, 161, 354 (1948).
4. Urey, H. C., and Craig, H., Geochim. et Cosmochim. Acta, 4, 36 (1953).
5. See, for example, the La Lande, New Mexico, chondrite. Beck, C. W., Stevenson, jun., R. G., and LaPaz, L., Pop. Astro., 59, No. 2, 93 ff. (February 1951).