Patera, J., Winternitz, P. and Sharp, and R. (1974) “Nagel-Moshinsky operators for discrete unitary representations of $U(p,q)$”, Revista Mexicana de Física, 23(1y2), pp. 81–98. Available at: https://rmf.smf.mx/ojs/index.php/rmf/article/view/1043 (Accessed: 5 July 2024).