Imash kyzy, M., F. G. Abdullayev, D. M. Bushev, and Yu. I. Kharkevych. “Isometry of the Subspacesof Solutions of Systems of Differential Equations to the Spaces of Real Functions”. Ukrains’kyi Matematychnyi Zhurnal 71, no. 8 (August 25, 2019): 1011-1027. Accessed April 24, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/1494.