F. Shipman, III, C. Marshall, und M. LeMere. Proceedings of the tenth ACM Conference on Hypertext and hypermedia : returning to our diverse roots: returning to our diverse roots, Seite 121--130. New York, NY, USA, ACM, (1999)
G. Stumme, R. Wille, und U. Wille. Principles of Data Mining and Knowledge Discovery, Volume 1510 von Lecture Notes in Computer Science, Springer, Berlin/Heidelberg, (1998)