Undoubtedly, the subject of this study (= over-popular Dirac
equation with Morse potential, known to be nicely solvable in
terms of hypergeometric functions, albeit de facto
approximatively, cf. [8] - [10]) belongs already to the textbooks
rather than to a scientific journal. Still, let me encourage all
the potential readers to pay attention because the present
Riccati-equation re-arrangement of the problem may be tricky:
about some of its puzzling aspects I know not only from the author
of the last reference [18].

This being said, one could  still feel unhappy with the story
which resembles strongly the ``exact WKB" approach of Voros et al,
without citing it at all. Moreover, knowing that ``... Ma and Xu
have found ... for the exactly solvable systems", no firm ground
seems to survive for the analogous work ``in Pekeris
approximation" (which we all know from its nice summary in the
book [7]).

Last but not least, one could encounter difficulties with
accepting some statements like, for example, the final sentence of
the methodical section II (``... Ma's exact quantization rule has
not yet been extended to the Dirac equation, but we can still use
it ..."). It sounds strange to my ears, indeed, though it may
easily be just my mistake (note that one of the key methodical
references is available just in Chinese).




MR2303274 Qiang, Wen-Chao; Zhou, Run-Suo; Gao, Yang Application of
the exact quantization rule to the relativistic solution of the
rotational Morse potential with pseudospin symmetry. J. Phys. A 40
(2007), no. 7, 1677--1685. 81Q05