KR.RANA, P. A STUDY OF THE GROUP OF COVERING TRANSFORMATION THROUGH FUNCTORS. Matematichki Bilten, [S. l.], v. 33, n. 1, 2009. Disponível em: https://bilten.smm.org.mk/index.php/bilten/article/view/1748. Acesso em: 13 jun. 2026.