ABUBAKAR, Rafiat Bada. A Note on Free Semigroups. Faculty of Natural and Applied Sciences Journal of Mathematical Modeling and Numerical Simulation, [S. l.], v. 2, n. 2, p. 1–9, 2025. Disponível em: https://fnasjournals.com/index.php/FNAS-JMNS/article/view/761. Acesso em: 10 may. 2025.