@article{wang2017main,
  title={A main directional maximal difference analysis for spotting facial movements from long-term videos},
  author={Wang, Su-Jing and Wu, Shuhang and Qian, Xingsheng and Li, Jingxiu and Fu, Xiaolan},
  journal={Neurocomputing},
  volume={230},
  pages={382--389},
  year={2017},
  publisher={Elsevier}
}