Meredith Stevenson and  John E. Porter,  Fuzzy Time Series Forecasting Using Percentage Change as the Universe of Discourse.   journal   = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology.
    July 2009, vol. 31(7). 464 - 467
    [viewed 11 May 2024]. Available from: https://publications.waset.org/pdf/7960.