JANEVA, B. FREE OBJECTS IN A VARIETY OF COMMUTATIVE VECTOR VALUED SEMIGROUPS. Matematichki Bilten, [S. l.], v. 17, n. 1, 1993. Disponível em: https://bilten.smm.org.mk/index.php/bilten/article/view/1526. Acesso em: 13 jun. 2026.