- Viola, Paul, and Michael J. Jones, Robust real-time face detection. International journal of computer vision: http://www.merl.com/publications/docs/TR2004-043.pdf
- Navneet Dalal and Bill Triggs, Histograms of Oriented Gradients for Human Detection: https://lear.inrialpes.fr/people/triggs/pubs/Dalal-cvpr05.pdf