KUCHARZEWSKI, Mieczysław. Über Eigenschaften gewisser Untermengen der Kleinschen Räume. Annales Mathematicae Silesianae, [S. l.], v. 4, p. 39–51, 1990. Disponível em: https://journals.us.edu.pl/index.php/AMSIL/article/view/14293. Acesso em: 5 dec. 2025.