“…As was shown recently [12], in case more information about the quantum system is available, then the Bohr-Sommerfeld rule can be modified to deliver exact results: knowledge of the potential and the quantum system's ground state are sufficient to predict the entire discrete energy spectrum in closed form. The such modified Bohr-Sommerfeld rule (called exact quantization formula) has been successfully tested on potentials that admit a discrete spectrum, including the Coulomb and harmonic oscillator case [12], Kratzer-type potentials [10], hyperbolic and Pöschl-Teller-like potentials [4], modified RosenMorse potentials [9], and many more. In contrast to these numerous applications in the conventional Schrödinger case, very little is known about quantization formulas and their application to other quantum-mechanical equations, such as the position-dependent mass Schrödinger equa-tion [16].…”