Bonatsos, D.; Daskaloyannis, C.; Kolokotronis, P.; Lenis, D. Nonlinear Extension of the u(3) Algebra As the Symmetry Algebra of the Three-Dimensional Anisotropic Quantum Harmonic Oscillator With Rational Ratios of Frequencies and the Nilsson Model. HNPS Adv Nucl Phys 2020, 5, 14-28.