K. Ganesan, C. Zhai, and J. Han. Proceedings of the 23rd International Conference on Computational Linguistics (Coling 2010), page 340--348. Beijing, China, Coling 2010 Organizing Committee, (August 2010)
A. Esuli, and F. Sebastiani. Proceedings of EACL-06, 11th Conference of the European Chapter of the Association for Computational Linguistics, Trento, IT., (2006)