Adil AL-Rammahi,  Calculus Logarithmic Function for Image Encryption .   journal   = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology.
    April 2014, vol. 87(3). 615 - 618
    [viewed 26 January 2020]. Available from: https://publications.waset.org/pdf/9998256.