ILIĆ, Ġ. Čupona, N. Celakoski, S. GROUPOID POWERS. Matematichki Bilten, [S. l.], v. 25, n. 1, 2001. Disponível em: https://bilten.smm.org.mk/index.php/bilten/article/view/1659. Acesso em: 13 jun. 2026.