@article{R. Anderson2018, author = "John R. Anderson and Ray Pelletier", title = "{A Development System for Model-Tracing Tutors}", year = "2018", month = "6", url = "https://kilthub.cmu.edu/articles/journal_contribution/A_Development_System_for_Model-Tracing_Tutors/6613103", doi = "10.1184/R1/6613103.v1" }