 Diatomic Molecules According to the Wave Mechanics. II. Vibrational Levels by Philip M. Morse

The original solution of the Morse potential model, with finite bound vibrational levels and anharmonic spacings. Physical Review 34, 57–64 (1929).

Author-version scan hosted by the University of Athens: jupiter.chem.uoa.gr/thanost/papers/papers4/PR_34%281929%2957.pdf