Kamalyan, H.A. “OPERATOR ANALOGUE OF BERNSTEIN THEOREM”. Proceedings of the YSU A: Physical and Mathematical Sciences 48, no. 1 (233) (April 10, 2014): 16–18. Accessed November 22, 2024. https://journals.ysu.am/index.php/proceedings-phys-math/article/view/vol48_no1_2014_pp016-018.