@Article{mlakar2015automated,<br />
 author= {U.~Mlakar and B.~Poto\v{c}nik},<br />
 title={Automated facial expression recognition based on histograms of oriented gradient feature vector differences},<br />
 journal={Signal, Image and Video Processing}, <br />
 year={2015},<br />
 volume={9},<br />
 pages={245--253},<br />
 publisher={Springer London}}