StrіletsO. “Reduction of the Gram Operator for Some Classes of the Systems of Subspaces”. Ukrains’kyi Matematychnyi Zhurnal 76, no. 5 (June 2, 2024): 765 - 775. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/7915.