Alberto Ceselli Roberto Cordone Marco Cremonini Balanced Clustering for Efficient Detection of Scientific Plagiarism. 163-170 2009 CTW http://www.lix.polytechnique.fr/ctw09/ctw09-proceedings.pdf#page=175 conf/colognetwente/2009 db/conf/colognetwente/colognetwente2009.html#CeselliCC09