KUCHARZEWSKI, Mieczysław. Über Eigenschaften gewisser Untermengen der Kleinschen Räume. Annales Mathematicae Silesianae, [S. l.], v. 4, p. 39–51, 1990. Disponível em: https://trrest.vot.pl/ojsus/index.php/AMSIL/article/view/14293. Acesso em: 7 may. 2025.