MASLYUCHENKO, V. K.; FOTII, O. H. Constancy of upper-continuous two-valued mappings into the Sorgenfrey line. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 59, n. 8, p. 1034–1039, 2007. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3367. Acesso em: 6 dec. 2025.