KHADSHIIVANOV, N.; STEFANOV, S. On the identification of points by continuous maps from the torus to the plane. Ann. Sofia Univ. Fac. Math. and Inf., [S. l.], v. 84, p. 91–96, 1993. Disponível em: https://stipendii.uni-sofia.bg/index.php/fmi/article/view/472. Acesso em: 5 dec. 2024.