1. in: Physics of Color Centers, Ed. Academic Press, New York 1968 (p. 133).
2. and , Electronic and Vibrational Properties of Point Defects in Ionic Crystals, North-Holland Publ. Co., Amsterdam 1979 (p. 123).
3. Dynamical Jahn-Teller Effect in Alkali Halide Phosphors Containing Heavy Metal Ions
4. and , see [3] (p. 193).