<Li> Jump up ^ Cyril Goutte, Lars Kai Hansen, Matthew G. Liptrot & Egill Rostrup (2001). "Feature - Space Clustering for fMRI Meta - Analysis". Human Brain Mapping. 13 (3): 165&ndash, 183 . doi: 10.1002 / hbm. 1031 . PMID 11376501 . CS1 maint: Multiple names: authors list (link) see especially Figure 14 and appendix . </Li> <Li> Jump up ^ Catherine A. Sugar; Gareth M. James (2003). "Finding the number of clusters in a data set: An information - theoretic approach". Journal of the American Statistical Association . 98 (January): 750&ndash, 763 . doi: 10.1198 / 016214503000000666 . </Li> <Li> Jump up ^ Peter J. Rousseuw (1987). "Silhouettes: a Graphical Aid to the Interpretation and Validation of Cluster Analysis". Computational and Applied Mathematics. 20: 53&ndash, 65 . doi: 10.1016 / 0377 - 0427 (87) 90125 - 7 . </Li> <Li> Jump up ^ R. Lleti; M.C. Ortiz; L.A. Sarabia; M.S. Sánchez (2004). "Selecting Variables for k - Means Cluster Analysis by Using a Genetic Algorithm that Optimises the Silhouettes". Analytica Chimica Acta. 515: 87&ndash, 100 . doi: 10.1016 / j. aca. 2003.12. 020 . </Li>

How to determine the number of clusters in a data set