GutikO. V., and ZarichnyiM. M. “Еhird Summer School Algebra, Analysis and Topology”. Ukrains’kyi Matematychnyi Zhurnal 58, no. 2 (February 25, 2006): 288-289. Accessed November 22, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3453.