J. Landay, und B. Myers. Proceedings of the SIGCHI conference on Human factors in computing systems, Seite 43--50. New York, NY, USA, ACM Press/Addison-Wesley Publishing Co., (1995)
K. Forbus, R. Ferguson, und J. Usher. Proceedings of the 6th international conference on Intelligent user interfaces, Seite 77--83. New York, NY, USA, ACM, (2001)