Harutyunyan, T.N. “LETTER TO THE EDITORIAL BOARD”. Proceedings of the YSU A: Physical and Mathematical Sciences 49, no. 2 (237) (June 12, 2015): 66. Accessed November 25, 2024. https://pub.ysu.am/index.php/proceedings-phys-math/article/view/vol49_no2_2015_pp066.