ZUBAIRU, M. .; LAWAN, Z. . On the monoid of partial isometries with fixed set. International Journal of Mathematical Analysis and Modelling, [S. l.], v. 7, n. 2, 2025. Disponível em: https://tnsmb.org/journal/index.php/ijmam/article/view/188. Acesso em: 28 jul. 2026.