C. Au Yeung, N. Gibbins, и N. Shadbolt. Proceedings of the 20th ACM conference on Hypertext and hypermedia
(HT2009), стр. 251--260. New York, NY, USA, ACM, (2009)
K. Bade, и D. Benz. Proceedings of the 32nd Annual Conference of the German Classification Society - Advances in Data Analysis, Data Handling and Business Intelligence (GfKl 2008), Berlin-Heidelberg, Springer, (2008)in press.