@misc {IOPORT.70771393,
    author       = {Ritter, Steven and Towle, Brendon and Murray, R. Charles and Hausmann, Robert G. M. and Connelly, John},
    title        = {Research-based improvements in cognitive tutor geometry},
    howpublished = {Intelligent Tutoring Systems (2), 452 (2010).},
    year         = {2010},
    doi          = {10.1007/978-3-642-13437-1_109},
    identifier   = {70771393},
}