L. P. Bedratyuk, “Poincare series of the multigraded algebras of SL 2-invariants”, Ukr. Mat. Zhurn., vol. 63, no. 6, pp. 755–763, Jun. 2011, Accessed: Feb. 16, 2026. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/2760