1. Bjerrum, N.: Nernst Festschrift, Halle, 1912.
2. Kratzer, A.: Z. Physik 3, 289 (1920).
3. See any (elementary) text on quantum mechanics, as well as: b) Dunham, J. L.: Phys. Rev. 41, 721 (1932), who discusses the Schrödinger rotatingvibrator for the first time, using the Wentzel-Brillouin-Kramers method; the internuclear potential V is developed in a power series about ξ=(r−r
e
)/r
e
=0. Dunham ascribes the fact that his treatment of the rotating-vibrator eight years after the formulation of quantum mechanics is the first paper in this field, to the success of Morse’s empirical function.
4. Morse, P. M.: Phys. Rev. 34, 57 (1929).
5. Nielsen, H. H.: The Vibration-rotation Energies of Molecules and their Spectra in the Infra-red. In: S. Flügge (Editor), Handbuch der Physik, Bd. XXXVII/1, Atome III-Moleküle I, p. 172–313. Berlin-Göttingen-Heidelberg: Springer 1959.