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. Saathoff, and S. Staab. 9th International Workshop on Image Analysis for Multimedia Interactive Services (WIAMIS 2008), page 16-19. Los Alamitos, CA, USA, IEEE Computer Society, (2008)