Arlinsky, Yu. M., and V. I. Mogilevskii. “Commuting Extensions of Operators”. Ukrains’kyi Matematychnyi Zhurnal 45, no. 6 (June 25, 1993): 744–752. Accessed April 11, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/5863.