Further reading[edit]
Kaufman, L.; Rousseeuw, P.J. (1990). Finding Groups in Data: An Introduction to Cluster Analysis (1 ed.). New York: John Wiley. ISBN 0-471-87876-6.
Hastie, Trevor; Tibshirani, Robert; Friedman, Jerome (2009). "14.3.12 Hierarchical clustering". The Elements of Statistical Learning (PDF) (2nd ed.). New York: Springer. pp. 520–528. ISBN 0-387-84857-6. Retrieved 2009-10-20.