Yasusi Kanada,  Natural-Direction-Consistent 3D-Design and Printing Methods.   journal   = {International Journal of Computer and Information Engineering}, [online]. World Academy of Science, Engineering and Technology.
    May 2015, vol. 100(4). 988 - 992
    [viewed 25 October 2021]. Available from: https://publications.waset.org/pdf/10001377.