1. G. Herzberg: Molecular Spectra and Molecular Structure I. Spectra of Diatomic Molecuels; II. Infrared and Raman Spectra of Polyatomic Molecules; and III. Electronic Spectra and Electronic Structure of Polyatomic Molecules (Van Nostrand, New York 1950; 1945; and 1966 )
2. C.H. Townes, A.L. Schawlow: Microwave Spectroscopy( McGraw-Hill, New York 1955 )
3. G. Jeung: J. Phys. B: At. Mol. Phys. 16, 4289 (1983)
4. Li Li, S.F. Rice, R.W. Field: J. Mol. Spectrosc. 105, 344 (1984)
5. Yao Zhao, Zhiye Shen, Qingshi Zhu, Cunhao Zhang: J. Mol. Spectrosc. 115, 34 (1986)