Takashi Mitsuishi and  Koji Saigusa,  Defuzzification of Periodic Membership Function on Circular Coordinates.   journal   = {International Journal of Computer and Information Engineering}, [online]. World Academy of Science, Engineering and Technology.
    September 2014, vol. 94(10). 1288 - 1291
    [viewed 12 July 2020]. Available from: https://publications.waset.org/pdf/9999436.