A. U. Klimyk, “Representations of the $q$-deformed algebra $U’_q(so_{2,2})$”, MFAT, vol. 3, no. 3, pp. 13–27, Sep. 1997, Accessed: Dec. 19, 2025. [Online]. Available: https://zen.imath.kiev.ua/index.php/mfat/article/view/41