Simsek, Emine, Iro Xenidou-Dervou, Ilyas Karadeniz, and Ian Jones. “The Conception of Substitution of the Equals Sign Plays a Unique Role in Students’ Algebra Performance”. Journal of Numerical Cognition 5, no. 1 (April 5, 2019): 24-37. Accessed May 14, 2024. https://jnc.psychopen.eu/index.php/jnc/article/view/5841.