1. Bethe H A 1929Ann. Physik 3 133
2. Dirac P A M 1964Lectures on Quantum Mechanics (New York, Belfer Graduate School of Science Yeshiva University)
3. Goldstein H 1952Classical Mechanics (Reading, Massachusetts, Addison-Wesley Publishing Co., Inc.)
4. Herzberg G 1945Infrared and Raman Spectra (Princeton, N. J., Van Nostrand)
5. Kiselev A A and Liapzev A V 1974Phys. Stat. Sol. (b)62 271