ArlinskyYu. M., and MogilevskiiV. I. “Commuting Extensions of Operators”. Ukrains’kyi Matematychnyi Zhurnal 45, no. 6 (June 25, 1993): 744–752. Accessed September 1, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5863.