@article{Opfer2018, author = "John E. Opfer and Robert Siegler", title = "{Representational change and children's numerical estimation.}", year = "2018", month = "6", url = "https://kilthub.cmu.edu/articles/journal_contribution/Representational_change_and_children_s_numerical_estimation_/6617924", doi = "10.1184/R1/6617924.v1" }