SEN, M.K.; AMERI, Reza; CHOWDHURY, Goutam. Hyperaction of semigroups and monoids. Italian Journal of Pure and Applied Mathematics, [S. l.], v. 28, p. 285–294, 2011. Disponível em: https://journals.uniurb.it/index.php/ijpam/article/view/5987. Acesso em: 18 jul. 2026.