L. Silva, и L. Jayaratne. Applications of Digital Information and Web Technologies, 2009. ICADIWT '09. Second International Conference on the, стр. 446-451. (августа 2009)
J. Tang, H. fung Leung, Q. Luo, D. Chen, и J. Gong. IJCAI'09: Proceedings of the 21st international jont conference on Artifical intelligence, стр. 2089--2094. San Francisco, CA, USA, Morgan Kaufmann Publishers Inc., (2009)