Najaryan, N.G. “COMPLETELY INVARIANT SUBSPACES OF FREE ALGEBRAS”. Proceedings of the YSU A: Physical and Mathematical Sciences 45, no. 1 (224) (February 16, 2011): 64–65. Accessed November 23, 2024. https://journals.ysu.am/index.php/proceedings-phys-math/article/view/vol45_no1_2011_pp064-065.