T. D. Gunneswara Rao and  Mudimby Andal ,  Cementing Efficiency of Low Calcium Fly Ash in Fly Ash Concretes.   journal   = {International Journal of Civil and Environmental Engineering}, [online]. World Academy of Science, Engineering and Technology.
    January 2013, vol. 84(12). 997 - 1001
    [viewed 12 November 2019]. Available from: https://publications.waset.org/pdf/9997297.