Dina K. Badawy and  Dina M. Ibrahim and  Alsayed A. Sallam,  A Query Optimization Strategy for Autonomous Distributed Database Systems.   journal   = {International Journal of Computer and Information Engineering}, [online]. World Academy of Science, Engineering and Technology.
    January 2018, vol. 135(3). 141 - 148
    [viewed 09 December 2021]. Available from: https://publications.waset.org/pdf/10008664.