@article{monteiro_drigo filho_2021,  title={Ladder Operators for the Spherical 3D Harmonic Oscillator},  volume={43},  ISSN={1806-1117},  url={https://doi.org/10.1590/1806-9126-RBEF-2020-0393},  DOI={10.1590/1806-9126-RBEF-2020-0393},  journal={Revista Brasileira de Ensino de Física},  publisher={Sociedade Brasileira de Física - SBF},  author={Monteiro, João Marcos Costa and Drigo Filho, Elso},  year={2021},  pages={e20200393} }