PetrenkoO. V., and ProtasovI. V. “Balleans and <i>G</I&gt; -Spaces”. Ukrains’kyi Matematychnyi Zhurnal 64, no. 3 (March 25, 2012): 344-350. Accessed November 22, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/2580.