Piette, B., & Vinet, L. (1987). Spectrum-generating algebras for the supersymmetric Morse and Pöschl-Teller Hamiltonians. Physics Letters. Section A: General, Atomic and Solid State Physics, 125(8), 380-384. https://doi.org/10.1016/0375-9601(87)90165-4 (Original work published 1987)