LEKKOKSUNG, Nareupanat; JAMPACHON, Prakit. IDEMPOTENT ELEMENTS OF PRE-GENERALIZED HYPERSUBSTITUTIONS OF TYPE (m, n). Italian Journal of Pure and Applied Mathematics, [S. l.], v. 36, p. 827–842, 2016. Disponível em: https://journals.uniurb.it/index.php/ijpam/article/view/6481. Acesso em: 16 aug. 2026.