1. N.V. Sidgwick, The Chemical Elements and their Compounds, Clarendon Press, Oxford, 1950, Vol. I, p. 334 et seq.
2. F.A. Cotton and G. Wilkinson, Advanced Inorganic Chemistry, 5th edn, Wiley-Interscience, New York, 1988, p. 162 et seq.
3. A. G. Sharpe, Inorganic Chemistry, 3rd edn, Longman, London, 1992, p. 254 et seq.
4. N.N. Greenwood and A. Earnshaw, Chemistry of the Elements, Pergamon Press, Oxford, 1984, p. 155 et seq.
5. D.F. Shriver, P.W. Atkins and C.H. Langford, Inorganic Chemistry, Oxford University Press, Oxford, 1990, p. 331 et seq.