VESTFRID, I. A. Near-isometries of the unit sphere. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 72, n. 4, p. 575–580, 2020. DOI: 10.37863/umzh.v72i4.6049. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/6049. Acesso em: 5 dec. 2025.