B. Ericson, M. Guzdial, and B. Morrison. Proceedings of the eleventh annual International Conference on International Computing Education Research, page 169-178. ACM, (August 2015)
T. Boyle, and M. Davies. Multimedia, Hypermedia, and Virtual Reality Models, Systems, and Applications, page 216--229. Berlin, Heidelberg, Springer Berlin Heidelberg, (1996)