Havlíček, M., Klimyk, A. U., & Pelantová, E. (1998). Representations of the $q$-deformed algebra U$_q$(so$_4$) for $q$ a root of unity. Methods of Functional Analysis and Topology, 4(3), 39-44. https://zen.imath.kiev.ua/index.php/mfat/article/view/66