1. K. W. Bagnall in G. Wilkinson, R. D. Gillard and J. A. McCleverty (Eds.),Comprehensive Coordination Chemistry, Pergamon Press, Oxford, 1987, Vol. 3, pp. 1211?1212.
2. J. L. Ryan in K. W. Bagnall (Ed.),Inorganic Chemistry, Series One, MTP International Review of Science, Butterworths, London, 1972, Vol. 7, pp. 340?341.
3. D. L. Perry, D. P. Freyberg and A. Zalkin,J. Inorg. Nucl. Chem.,42, 243 (1980).
4. G. Vanden Bossche,Acta Crystallogr., C,43, 383 (1987).
5. V. P. Markov and V. V. Tsapkin,Russ. J. Inorg. Chem.,6, 1052 (1961).