1. N. N. Greenwood and E. Earnshaw, Chemistry of the Elements (Pergamon, Oxford, 1984), p. 466.
2. J. W. Mellor, Comprehensive Treatise on Inorganic and Theoretical Chemistry (Wiley, New York, 1922), Vol. VIII.
3. A. V. Leont–ev, O. A. Fomicheva, M. V. Proskurnina and N. S. Zefirov, Russ. Chem. Rev. 70, 91 (2001).
4. B. Wang and X.-Y. Li, Anal. Chem. 70, 2181 (1998).
5. W. J. Grant, Medical Gases: Their Properties and Uses (HM+M Publishers, Aylesbury, 1978).