1. L. Kaufman, P.J. Rousseeuw, Finding Groups in Data — An Introduction to Cluster Analysis, Wiley, NY, 1989.
2. H. Spath, Cluster Analysis — Algorithms for Data Reduction and Classification of Objects Ellis Horwood Limited, West Sussex, UK, 1980.
3. V. Susheela Devi, M. Narasimha Murty, in: Sankar K. Pal, A. Ghosh, M.K. Kundu (Eds.), Handwritten Digit Recognition Using Soft Computing, Physica-Verlag, Berlin, 2000.
4. E.I. Chang, R.P. Lippmann, Using genetic algorithms to improve pattern classification performance, Advances in Neural Information Processing Systems 3, Morgan Kaufman, Los Attos, CA, 1990, pp. 797–803.
5. Growing subspace pattern recognition methods and their neural-network models