LIVINSKY, I.V.; ZHUKOVSKA, T.G. On orders of two transformation semigroups of the boolean. Carpathian Mathematical Publications, [S. l.], v. 6, n. 2, p. 317–319, 2014. DOI: 10.15330/cmp.6.2.317-319. Disponível em: https://ktipe.pnu.edu.ua/index.php/cmp/article/view/1362. Acesso em: 16 may. 2025.