1. G. Herzberg: Molecular Spectra and Molecular Structure, Vols. I, II and III (Van Nostrand Reinhold New York 1945, 1950, 1966)
2. G. Herzberg: The Spectra and Structures of Simple Free Radicals, An Introduction to Molecular Spectroscopy (Cornell Univ. Press, Ithaca 1971)
3. M.R. Robin: Higher Excited States of Polyatomic Molecules, Vols. I and II (Academic Press, New York 1974, 1975)
4. H.H. Jaffé, M. Orchin: Theory and Applications of Ultraviolet Spectroscopy (Wiley, New York 1962)
5. Chemical Spectroscopy and Photochemistry in the Vacuum-Ultraviolet ed. by C. Sandorfy, P.J. Ausloos and M.B. Robin (Reidel Publ. Company, Dordrecht-Holland 1974)