IVANYUTA, I. D. On relatively free groups close to metabelian ones . Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 23, n. 1, p. 93–96, 1970. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8486. Acesso em: 5 dec. 2025.