Berry, John, Roger Fentem, Anna-Maija Partanen, and Sirkka Tiihala. “The Use of Symbolic Algebra in Learning Mathematics: The Barrier from Formal Examination Schemes”. NOMAD Nordic Studies in Mathematics Education 9, no. 4 (December 10, 2004): 49–64. Accessed December 5, 2024. https://tidsskrift.dk/NOMAD/article/view/147151.