1. H. G. Drickamer and C. W. Frank, Electronic Transitions and the High Pressure Chemistry and Physics of Solids, Chapman and Hall, London (1973).
2. G. A. Samara, in Proc. 4th Intern. High Pressure Conference, The Physico-Chemical Soc. of Japan, Kyoto, Japan (1974), p. 247.
3. S. Minomura, B. Okai, Y. Onoda, and S. Tanuma, Phys. Letters 23, 641 (1966).
4. H. Sawamoto, E. Ohtani and M. Kumazawa, in Proc. 4th Intern. High Pressure Conference, The Physico-Chemical Soc. of Japan, Kyoto, Japan (1974), p. 194.
5. A. E. Ringwood, Composition and Petrology of the Earth’s Mantle, McGraw-Hill, New York (1975); also The Nature of the Solid Earth, E. C. Robertson, ed., McGraw Hill, New York (1972); G. A. Samara, J. Geophysical Research 72, 671 (1967).