1. Mann-Whitney-Wilcoxon test online. http://www.socscistatistics.com/tests/mannwhitney/Default2.aspx.
2. Sourceforge online SVN repository. http://sourceforge.net/.
3. How clones are maintained: an empirical study;Aversano,2007
4. An investigation of the fault-proneness of clone evolutionary patterns;Barbour;Softw. Qual. J.,2017
5. Late propagation in software clones;Barbour,2011