Breus К. A. Otto Yulyevich Schmidt (on his seventy fifth anniversary). Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 18, n. 5, p. 3–6, 1966. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8435. Acesso em: 6 dec. 2025.