Bedratyuk, L. P. “Poincare Series of the Multigraded Algebras of SL 2-Invariants”. Ukrains’kyi Matematychnyi Zhurnal 63, no. 6 (June 25, 2011): 755–763. Accessed December 5, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/2760.