Girish Kumar Singh and  Sonajharia Minz,  Granulation using Clustering and Rough Set Theory and its Tree Representation .   journal   = {International Journal of Computer and Information Engineering}, [online]. World Academy of Science, Engineering and Technology.
    January 2007, vol. 1(1). 113 - 118
    [viewed 19 September 2020]. Available from: https://publications.waset.org/pdf/14084.