Błaszczyk, Piotr, and Mirosława Sajka. “On the Negative Numbers from the Historical and Educational Perspective”. Annales Universitatis Paedagogicae Cracoviensis | Studia ad Didacticam Mathematicae Pertinentia 9, no. 1 (June 1, 2018): 5–36. Accessed April 30, 2024. https://didacticammath.uken.krakow.pl/article/view/4325.