BedratyukL. P. “Kernels of Derivations of Polynomial Rings and Casimir Elements”. Ukrains’kyi Matematychnyi Zhurnal 62, no. 4 (April 25, 2010): 435–452. Accessed November 24, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/2878.