1. A. B. P. Lever:Inorganic Electronic Spectroscopy, second edition (Elsevier, 1984).
2. N. S. Hush andR. J. M. Hobbs:Progress in Inorganic Chemistry, V. 10, edited byF. A. Cotton (Interscience, 1968).
3. M. A. Hitchmann:Transition Metal Chemistry, V. 9, edited byG. A. Melson andB. N. Figgis.
4. P. J. McCarthy andH. U. Güdel,Coord. Chem. Rev.,88, 69 (1988).
5. D. Talapatra andR. K. Mukherjee:Phys. Status Solidi B,155, 541 (1989).