1. Han J, Kamber M, Pei J (2011) Data mining: concepts and techniques, 3rd edn. Morgan Kaufmann, Waltham, pp 65–76
2. Pei-Ying Y, Da-Lin W (2007) Dissimilar metric and clustering for hierarchy variable. Comput Sci 34(10):214–216
3. Joshi R, Patidar A, Mishra S (2001) Scaling k-medoid algorithm for clustering large categorical dataset and its performance analysis. In: International conference on electronic computer technology, Kanyakumari, India, pp 117–121
4. Serguei Levachkine, Adolfo Guzmán-arenas (2004) Hierarchies measuring qualitative variables. Lecture notes in computer science 2945. Springer, Seoul, South Korea, pp 262–274