ITS Technologies in Virtual Environments: Can We Harness the Synergy? - Carol D. Horwitz; Jeff Rickel; Allen Munro; Craig R. Hall; Randy Stiles; Helen M. Gigley (Intelligent Tutoring Systems, 1998)

Virtual reality for training: evaluating knowledge retention. - Craig R. Hall; Randy Stiles; Carol D. Horwitz (VRAIS, 1998)

Virtual Reality for Training: Evaluating Retention of Procedural Knowledge. - Craig R. Hall; Carol D. Horwitz (Int. J. Virtual Real., 2001)