X. Li, L. Chen, L. Zhang, F. Lin, and W. Ma. MULTIMEDIA '06: Proceedings of the 14th annual ACM international conference on Multimedia, page 607--610. New York, NY, USA, ACM, (2006)
C. Wu, L. Huang, and L. Kang. Proceedings of 2005 International Conference on
Machine Learning and Cybernetics, 5, page 2870--2873. IEEE, (18-21 August 2005)