Cholewa, P. W. (1986) “Duality principle of W. Sierpiński in the abstract Baire-cathegory theory”, Annales Mathematicae Silesianae, 2, pp. 30–36. Available at: https://trrest.vot.pl/ojsus/index.php/AMSIL/article/view/14315 (Accessed: 8 May 2025).