1. C. N. R. Rao, “Chemical Applications of Infrared Spectroscopy,” Academic Press, 1963.
2. B. N. Figgis, J. Lewis and R. G. Wilkins, “Modern Coordination Chemistry,” ed. by J. Lewis & R. G. Wilkins, Interscience, New York, 1960, p. 403.
3. F. A. Cotton and G. Wilkinson, “Advanced Inorganic Chemistry,” Wiley, New York, 1976, p. 916.