S. Saini, and M. Aggarwal. ICAI'07: Proceedings of the 8th Conference on 8th WSEAS International Conference on Automation and Information, page 252--257. Stevens Point, Wisconsin, USA, World Scientific and Engineering Academy and Society (WSEAS), (2007)
Y. Cao, and Q. Zhu. ICYCS '08: Proceedings of the 2008 The 9th International Conference for Young Computer Scientists, page 742--747. Washington, DC, USA, IEEE Computer Society, (2008)