Amitava Chakraborty and  Sudip Kumar De and  Ranjan Dasgupta,  Balancing of Quad Tree using Point Pattern Analysis.   journal   = {International Journal of Computer and Information Engineering}, [online]. World Academy of Science, Engineering and Technology.
    April 2011, vol. 52(4). 362 - 365
    [viewed 18 November 2019]. Available from: https://publications.waset.org/pdf/12292.