WASET
    Ahmad R. Naghsh-Nilchi and  Mohammad Roshanzamir,  An Efficient Algorithm for Motion Detection Based Facial Expression Recognition using Optical Flow.   journal   = {International Journal of Computer and Information Engineering}, [online]. World Academy of Science, Engineering and Technology.
    August 2008, vol. 20(8). 2724 - 2729
    [viewed 24 April 2024]. Available from: https://publications.waset.org/pdf/6512.