1. Ballhausen, C. J.: Introduction to ligand field theory. New York-Toronto-London: McGraw-Hill 1962.
2. Jørgensen, C. K.: Absorption spectra and chemical bonding in complexes. Oxford-London-New York-Paris: Pergamon Press 1962.
3. Klick, C. C., andJ. H. Schulman: Solid state physics, Vol. 5, (Ed. bySeitz, F., andD. Turnbull). New York: Academic Press 1957.
4. Porter, G. B., u.H. L. Schläfer: Ber. Bunsenges. physik. Chemie68, 316 (1964).
5. — —: Z. physik. Chemie N. F.40, 280 (1964).