Index of volume 71 of „Ukrainian Mathematical Journal”. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 71, n. 12, p. 1723–1728, 2020. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2290. Acesso em: 5 dec. 2025.