UŠAN, J. ON (k(n-1)+l)-SEMIGROUPS WITH (n-2)-NEUTRAL OPERATIONS. Matematichki Bilten, [S. l.], v. 22, n. 1, 1998. Disponível em: https://bilten.smm.org.mk/index.php/bilten/article/view/1583. Acesso em: 13 jun. 2026.