Dawidowicz, Antoni Leon. “How to Solve Third Degree Equations Without Moving to Complex Numbers”. Annales Universitatis Paedagogicae Cracoviensis | Studia ad Didacticam Mathematicae Pertinentia 12 (December 31, 2020): 123–131. Accessed May 5, 2024. https://didacticammath.uken.krakow.pl/article/view/8464.