1. J.K.G. Watson, Aspects of quartic and sextic centrifugal effects on rotational energy levels, vol. 6 in: M. Dekker (Ed.), Vibrational Spectra and Structures, Dekker, New York, 1977.
2. Electronic Spectra of Polyatomic Molecules;Herzberg,1988
3. Ground state constants and K-type doubling for allene
4. The vibration-rotation energies of tetrahedral XY4 molecules
5. Calculation of the frequencies of the lines in a threefold degenerate fundamental band of a spherical top molecule