Hilbert, David. “O pojęciu Liczby”. Annales Universitatis Paedagogicae Cracoviensis | Studia ad Didacticam Mathematicae Pertinentia 4 (July 5, 2017): 199–202. Accessed June 7, 2025. https://didacticammath.uken.krakow.pl/article/view/3672.