Shenghua Gao, Liang-Tien Chia, Ivor Wai-Hung Tsang. Multi-layer group sparse coding - For concurrent image classification and annotation. In The 24th IEEE Conference on Computer Vision and Pattern Recognition, CVPR 2011, Colorado Springs, CO, USA, 20-25 June 2011. pages 2809-2816, IEEE, 2011. [doi]