Non-Negative Integer Matrix Representations of a $\mathbb{Z}_{+}$-Ring. Journal of Mathematical Study, [S. l.], v. 54, n. 4, p. 357–370, 2021. DOI: 10.4208/jms.v54n4.21.02. Disponível em: https://www.global-sci.com/index.php/jms/article/view/13399. Acesso em: 6 dec. 2025.