, Editorial Board of the Ukrainian Mathematical Journal. Leonid Pavlovych Nyzhnyk (on his 90th birthday). Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 77, n. 7, p. 495–500, 2025. DOI: 10.3842/umzh.v77i7.9395. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/9395. Acesso em: 5 dec. 2025.