UŠAN, Janez. ON \((k(n-1)+1)\)-SEMIGROUPS WITH \((n-2)\)-NEUTRAL OPERATIONS. Matematichki Bilten, [S. l.], v. 22, n. 1, p. 5–14, 1998. Disponível em: https://bilten.smm.org.mk/index.php/bilten/article/view/1583. Acesso em: 14 aug. 2026.