1. P. George. J. Chem. Soc. (1955), p. 2367.
2. J. Bennet. Phil. Mag. 46: 443 (1955).
3. W. J. Sax. Dangerous Properties of Industrial Materials, New York, Reinhold Publishing Corp. (1962), p. 1127.
4. A. J. Cohen and J. Margrave. Anal. Chem. 29: 1462 (1957).
5. J. Kleinberg. Unfamiliar Oxidation States and Their Stabilization, Lawrence, Kansas (1950).