Anderson, R. L., Sukeyuki Kumei., and and C. E. Wulfman. “Invariants of the Equations of Wave Mechanics II. One-Particle Schröedinger Equations”. Revista Mexicana De Física, vol. 21, no. 1, Jan. 1972, pp. 35-57, https://rmf.smf.mx/ojs/index.php/rmf/article/view/999.