Fotiy, O., M. Ostrovskii, and M. Popov. “Isomorphic Spectrum and Isomorphic Length of a Banach Space”. Carpathian Mathematical Publications 12, no. 1 (June 12, 2020): 88–93. Accessed April 20, 2024. https://scijournals.pnu.edu.ua/index.php/cmp/article/view/3879.