M. Freiberg, und J. Baumeister. 450. University of Würzburg, Institute of Computer Science, Department of Artificial Intelligence and Applied Informatics, Am Hubland, D-97074 Würzburg, Germany, (2008)
A. Weingessel, E. Dimitriadou, und S. Dolnicar. Working Paper 29. SFB ``Adaptive Information Systems and Modeling in Economics and Management Science'', (1999)