BerezanskyYu. M., GorbachukV. I., and GorbachukM. L. “Functional Analysis in the Institute of Mathematics of the National Academy of Sciences of Ukraine”. Ukrains’kyi Matematychnyi Zhurnal 57, no. 5 (May 25, 2005): 582–600. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3625.