@article{Long2018, author = "Yanjin Long", title = "{Supporting Learner-Controlled Problem Selection in Intelligent Tutoring Systems}", year = "2018", month = "7", url = "https://kilthub.cmu.edu/articles/thesis/Supporting_Learner-Controlled_Problem_Selection_in_Intelligent_Tutoring_Systems/6723413", doi = "10.1184/R1/6723413.v1" }