Y. M. Berezansky, V. I. Gorbachuk, and M. L. Gorbachuk, “Functional Analysis in the Institute of Mathematics of the National Academy of Sciences of Ukraine”, Ukr. Mat. Zhurn., vol. 57, no. 5, pp. 582–600, May 2005, Accessed: Dec. 05, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/3625