1. 1. W. B. Frakes, R. Baeza and Yates, Information Retrieval: Data Structures & Algorithms, Prentice Halls, 2004.
   2. C. J. v. RIJSBERGEN , INFORMATION RETRIEVAL, London: Butterworths, 1979.
   3. S. F. Dierk, "The SMART retrieval system: Experiments in automatic document processing," in IEEE Transactions on Professional Communication, Princeton, N.J, 1972.
   4. Winston and P. Henry, Artificial intelligence, IBEROAMERICANA: ADDISON WESLEY, 1994. [5] R. J. Stuart and N. Peter, Artificial Intelligence : A Modern Approach, Prentice Hall, 1996.
   5. B. W. Michael, Survey of Text Mining, Verlag New York: Springer, 2004.
   6. B. W. Michael and C. Malu, Survey of Text Mining II, Verlag London: Springer, 2008
   7. T. M. Mitchell, Machine Learning, McGraw-Hill Education, 1997.
   8.  C. Felix, V. Alfredo, N. Angela and F. Mujica, "Applying Data Mining Techniques to e-Learning Problem," in Evolution of Teaching and Learning Paradigms in Intelligent Environment, Springer, 2007, pp. 183-222
   9. A. E. Eiben, R. Hinterding and Z. Michalewicz, "Parameter control in evolutionary algorithms," IEEE Transactions on Evolutionary Computation, vol. 3, no. 2, pp. 124- 141, 1999.
   10. J. J. Grefenstette, Genetic Algorithms for Machine Learning, Netherlands: Kluwer Academic Publishers, 1995.
   11. S. F. Dierk, "The SMART retrieval system: Experiments in automatic document processing," IEEE Transactions on Professional Communication, vol. 15, no. 1, pp. 17-17, 1972.
   12. N. Fuhr, "Probabilistic Models in Information Retrieval," Computer Journal, vol. 35, no. 3, pp. 243-55, 1992.
   13.  A. Bookstein, "Outline of a General Probabilistic Retrieval Model," Journal of Documentation, vol. 39, no. 2, pp. 63- 72, 1983.
   14. D. Lewis, "text categorization test collection," Reuters, 1997