1. Bleaney, B., and Bowers, K. D., Proc. Roy. Soc., A, 214, 451 (1952).
2. Van Niekerk, J. N., and Schoening, F. R. L., Nature, 171, 36 (1953); Acta Cryst., 6, 227 (1953).
3. Abe, H., Phys. Rev., 92, 1572 (1953).
4. Tsuchida, R., and Kobayashi, M., Bull. Chem. Soc. Japan, 13, 619 (1938); “The Colour and the Structure of Metallic Compounds” (Osaka, 1944).
5. For example, French, H. S., and Lowry, T. M., Proc. Roy. Soc., A, 106, 489 (1924), etc. They called the absorption band of this kind a “copper band”.