\begin{thebibliography}{1}

\bibitem{byrn99}
R.~A. Baeza-Yates and B.~Ribeiro-Neto, editors.
\newblock {\em Modern Information Retrieval}.
\newblock Addison-Wesley, 1999.

\bibitem{cohen95r}
W.~Cohen.
\newblock Fast effective rule induction.
\newblock In {\em ICML'95}, pages 115--123, 1995.
\newblock Available on-line from
  \url{http://www.cs.cmu.edu/~wcohen/postscript/ml-95-ripper.ps}.

\bibitem{demsar06}
J.~Demsar.
\newblock Statistical comparisons of clasifiers over multiple data sets.
\newblock {\em Journal of Machine Learning Research}, 7:1--30, 2006.
\newblock Avaliable from
  \url{http://jmlr.csail.mit.edu/papers/v7/demsar06a.html}.

\bibitem{porter80}
M.~Porter.
\newblock An algorithm for suffix stripping.
\newblock In K.~S. Jones and P.~Willet, editors, {\em Readings in Information
  Retrieval, San Francisco: Morgan Kaufmann}. 1997.

\bibitem{salton83introduction}
G.~Salton and M.~J. McGill.
\newblock {\em Introduction to Modern Information Retrieval}.
\newblock McGraw Hill, 1983.

\bibitem{witten99}
I.~H. Witten and E.~Frank.
\newblock {\em Data Mining: Practical Machine Learning Tools and Techniques
  with Java Implementations}.
\newblock Morgan Kaufmann, 1999.

\bibitem{witten05}
I.~H. Witten and E.~Frank.
\newblock {\em Data mining. 2nd edition}.
\newblock Morgan Kaufmann, Los Altos, US, 2005.

\end{thebibliography}
