Gilmore, Camilla, Sarah Keeble, Sophie Richardson, and Lucy Cragg. “The Interaction of Procedural Skill, Conceptual Understanding and Working Memory in Early Mathematics Achievement”. Journal of Numerical Cognition 3, no. 2 (December 22, 2017): 400-416. Accessed December 9, 2021. https://jnc.psychopen.eu/index.php/jnc/article/view/5745.