Yeqing Guan and  Fen Yang,  Application of GM (1, 1) Model Group Based on Recursive Solution in China's Energy Demand Forecasting.   journal   = {International Journal of Economics and Management Engineering}, [online]. World Academy of Science, Engineering and Technology.
    August 2012, vol. 68(8). 2059 - 2062
    [viewed 26 April 2024]. Available from: https://publications.waset.org/pdf/2637.