PLEWIK, Szymon. A theorem on spaces of finite subsets. Annales Mathematicae Silesianae, [S. l.], v. 2, p. 108–110, 1986. Disponível em: https://trrest.vot.pl/ojsus/index.php/AMSIL/article/view/14331. Acesso em: 4 jul. 2025.