ARZHANTSEV, I. V.; PETRAVCHUK, A. P. Closed polynomials and saturated subalgebras of polynomial algebras. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 59, n. 12, p. 1587–1593, 2007. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3414. Acesso em: 6 dec. 2025.