1. Spectroscopic Properties of Rare Earths;Wybourne,1965
2. Multiplets of Transition-Metal Ions in Crystals;Sugano,1970
3. Optical Spectra of Transparent Rare Earth Compounds;Hüfner,1978
4. Introduction to Ligand Fields;Figgis,1966
5. Angular Momentum Theory Applied to Interactions in Solids;Morrison,1988