Karakhanyan, I. M., and M. I. Karakhanyan. “SUBNORMALITE OF BANACH ALGEBRA”. Proceedings of the YSU A: Physical and Mathematical Sciences 42, no. 1 (215) (September 6, 2023): 10–17. Accessed July 22, 2024. https://journals.ysu.am/index.php/proceedings-phys-math/article/view/vol42_no1_2008_p010-017.