G. Davis, and M. Mcgowen. proceedings of the Annual Meeting of the 26th Annual Meeting of the International Group for the Psychology of Mathematics Education (PME), 2, page 273-280. Norwich, UK, University of Norwich, (July 2002)
I. Zitter, G. Kinkhorst, R. jan Simons, and O. ten Cate. Computers in Human Behavior, 25 (5):
999 - 1009(2009)Including the Special Issue: Design Patterns for Augmenting E-Learning Experiences.