M. Schiller, und C. Benzmüller. Artificial Intelligence in Education -- Building Learning Systems tat Care: From Knowledge Representation to Affective Modelling, 200, Seite 599--601. Amsterdam, IOS Press, (2009)
W. Harrison, H. Ossher, und M. Kavianpour. Proceedings of the 5th International Workshop on Computer-Aided Software engineering, Seite 23--35. Montreal, Canada, (Juli 1992)