Carol Horwitz Jeff Rickel Allen Munro Craig Hall Randy Stiles Helen M. Gigley ITS Technologies in Virtual Environments: Can We Harness the Synergy? 617 http://dx.doi.org/10.1007/3-540-68716-5_91 1998 conf/its/1998 Intelligent Tutoring Systems db/conf/its/its1998.html#HorwitzRMHSG98