参考：@inproceedings{zhang15_cvpr,
 Author = {Xucong Zhang and Yusuke Sugano and Mario Fritz and Bulling, Andreas},
 Title = {Appearance-based Gaze Estimation in the Wild},
 Booktitle = {Proc. of the IEEE International Conference on Computer Vision and Pattern Recognition (CVPR)},
 Year = {2015}, Month = {June}
 Pages = {4511-4520}
 }