Iwona Bak, Magdalena Ziolo, Katarzyna Cheba, Anna Spoz. “Column Equation Solving Problems in Middle School Exam Paper”. CEMJP 23, no. 3 (September 1, 2015): 1–12. Accessed November 23, 2024. http://journals.kozminski.cem-j.org/index.php/pl_cemj/article/view/352.