Fatima Akhmedova and  Simon Liao,  Face Recognition Using Discrete Orthogonal Hahn Moments.   journal   = {International Journal of Computer and Information Engineering}, [online]. World Academy of Science, Engineering and Technology.
    August 2015, vol. 102(6). 1550 - 1556
    [viewed 15 December 2019]. Available from: https://publications.waset.org/pdf/10002256.