LEVIN, B. Ya. Mark Grigor’evich Krein (recollections). Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 46, n. 3, p. 305–309, 1994. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5763. Acesso em: 5 dec. 2025.