PLAKSA, S. A. On the composition of operators in vector spaces and their Noether property. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 45, n. 8, p. 1177–1180, 1993. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5918. Acesso em: 5 dec. 2025.