1. Cox and Webster, J. Chem. Soc., 1635 (1936). See also Sidgwick, “The Chemical Elements and Their Compounds”, 183 et seq. (Oxford, 1950).
2. Selwood, “Magnetochemistry”, 103, 182 (Interscience, 1943).
3. Wells, H. L., Amer. J. Sci., 3, 315, 417 (1922).
4. Mann and Purdie, J. Chem. Soc., 1235 (1940).
5. Sidgwick, “The Chemical Elements and Their Compounds”, 137 et seq. (Oxford, 1950).