BĄK, Judyta; KUCHARSKI, Andrzej. Topological spaces with the Freese–Nation property. Annales Mathematicae Silesianae, [S. l.], v. 33, p. 41–54, 2019. Disponível em: https://journals.us.edu.pl/index.php/AMSIL/article/view/13649. Acesso em: 5 dec. 2025.