Robert G. M. Hausmann Timothy J. Nokes Kurt VanLehn Brett van de Sande Collaborative Dialog While Studying Worked-out Examples. 596-598 2009 AIED http://dx.doi.org/10.3233/978-1-60750-028-5-596 conf/aied/2009 db/conf/aied/aied2009.html#HausmannNVS09