Prabhu, Puniethaa, and Karuppusamy Duraiswamy. “An Efficient Visual Analysis Method for Cluster Tendency Evaluation, Data Partitioning and Internal Cluster Validation”. Computing and Informatics, vol. 32, no. 5, Jan. 2014, pp. 1013-37, http://147.213.75.17/ojs/index.php/cai/article/view/1982.