TUSHEV, A. V. On solvable groups, all proper factor groups of which have finite ranks. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 45, n. 9, p. 1274–1281, 1993. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5930. Acesso em: 5 dec. 2025.