1. Wilson, E. B., Howard, J. B.: J. Chem. Phys. 4, 260 (1936)
2. Wilson, E. B., Decius, J. C., Cross, P. C.: Molecular vibrations. New York: McGraw-Hill 1955
3. Wilson, E. B.: J. Chem. Phys. 7, 1047 (1939) and 9, 76 (1941)
4. Amat, G., Nielsen, H. H., Tarrago, G.: Rotation vibration of polyatomic molecules. New York: Marcel Dekker, Inc. 1971
5. Mills, I. M.: Vibration-rotation structure in asymmetric-and symmetric-top molecules. In: Molecular spectroscopy: Modern research. Rao, K. N., Mathews, C. W. (ed.). New York-London: Academic Press 1972