TARGOŃSKI, Győrgy; ZDUN, Marek Cezary. Generators and co-generators of substitution semigroups. Annales Mathematicae Silesianae, [S. l.], v. 1, p. 169–174, 1985. Disponível em: https://journals.us.edu.pl/index.php/AMSIL/article/view/14348. Acesso em: 5 dec. 2025.