Vukman, Joso, and Irena Kosi-Ulbl. “On Two-Sided Centralizers of Rings and Algebras”. CUBO, A Mathematical Journal 10, no. 3 (October 1, 2008): 211–222. Accessed May 4, 2024. https://cubo.ufro.cl/ojs/index.php/cubo/article/view/1511.