Duran, B. S., and Odell, P. L. (1974). Cluster Analysis. New York: Springer-Verlag.
Everitt, B. S. (1980). Cluster Analysis. 2nd ed. London: Heineman Educational Books.
Fisher, R. A. (1936). “The Use of Multiple Measurements in Taxonomic Problems.” Annals of Eugenics 7:179–188.
Hand, D. J., Daly, F., Lunn, A. D., McConway, K. J., and Ostrowski, E. (1994). A Handbook of Small Data Sets. London: Chapman & Hall.
Hartigan, J. A. (1975). Clustering Algorithms. New York: John Wiley & Sons.
Johnson, S. C. (1967). “Hierarchical Clustering Schemes.” Psychometrika 32:241–254.
Knuth, D. E. (1973). Fundamental Algorithms. Vol. 1 of The Art of Computer Programming. Reading, MA: Addison-Wesley.