PilipenkoA. Yu. “On Local Operators Diagonal With Respect to the System of Hermitian Polynomials”. Ukrains’kyi Matematychnyi Zhurnal 47, no. 4 (April 25, 1995): 555–561. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5457.