Ryan Shaun Joazeiro de Baker M. P. Jacob Habgood Shaaron Ainsworth Albert T. Corbett Modeling the Acquisition of Fluent Skill in Educational Action Games. 17-26 2007 conf/um/2007 User Modeling http://dx.doi.org/10.1007/978-3-540-73078-1_5 db/conf/um/um2007.html#BakerHAC07