On the identification of points by continuous maps from the torus to the plane. Annual of Sofia University St. Kliment Ohridski. Faculty of Mathematics and Informatics, [S. l.], v. 84, p. 91–96, 1993. Disponível em: https://annual.uni-sofia.bg/index.php/fmi/article/view/472. Acesso em: 4 feb. 2026.