1. G. Herzberg, Molecular Spectra and Molecular Structure. I. Diatomic Molecules, 2nd edn. (Van Nostrand, New York, 1950), p. 92
2. J.E. Mayer, M. Goeppert-Mayer, Statistical Mechanics (Wiley, New York, 1940)
3. K.P. Huber, G. Herzberg, Molecular Spectra and Molecular Structure. IV. Constants of Diatomic Molecules (Van Nostrand, New York, 1979). See also NIST Chemistry WebBook, https://webbook.nist.gov/
4. L.S. Kassel, Chem. Rev. 18, 277 (1936)
5. D.A. McQuarrie, Mathematical Methods for Scientists and Engineers (University Science Books, Sausalito, 2003), pp. 107–112