1. Molecular Spectra and Molecular Structure;Herzberg,1991
2. Molecular Spectra and Molecular Structure;Herzberg,1991
3. Molecular Symmetry and Spectroscopy;Bunker,1998
4. P.R. Bunker, P. Jensen, Fundamentals of Molecular Symmetry. Institute of Physics Publishing, Bristol and Philadelphia, 2005.
5. High Resolution Spectroscopy;Hollas,1992