A naive rediscovery of what is known as supersymmetric quantum
mechanics in its particular, so called coordinate-dependent-mass
dynamical regime (cf. [15]). The authors felt inspired by ref. [9]
but they should have also noticed the existence of many other
subsequent relevant references (e.g., J. F. Carinena, M. F. Ranada
and M. Santander, Annals Phys. 322: 434-459, 2007, etc).

MR2821748 Wang, Xue-Hong; Liu, Yu-Bin Factorization method for a
class of quantum nonlinear harmonic oscillators. Internat. J.
Theoret. Phys. 50 (2011), no. 9, 2697--2702. 81Qxx