1. Very large two-level SOM for the browsing of newsgroups;Kohonen,1996
2. Some methods for classification and analysis of multivariate observations;MacQueen,1967
3. Finding Groups Data: Introduction to Cluster Analysis;Kaufman,1990
4. Data Clustering: a review;Jain;ACM Comput. Surv.,1999
5. A density-based algorithm for discovering clusters in large spatial databases with noise;Ester,1996