CHERNIKOV, S. N. Otto Yulievich Shmidt (on his 80th birth) . Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 23, n. 5, p. 581–585, 1971. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8328. Acesso em: 5 dec. 2025.