Ambrus, András, and Krisztina Barczi-Veres. “Using Open Problems and Cooperative Methods in Mathematics Education”. LUMAT: International Journal on Math, Science and Technology Education 3, no. 1 (February 28, 2015): 3–18. Accessed September 20, 2024. https://journals-21.hulib.helsinki.fi/lumat/article/view/1048.