Anas M. Fares,  Effect of Columns Stiffness's and Number of Floors on the Accuracy of the Tributary Area Method.   journal   = {International Journal of Civil and Environmental Engineering}, [online]. World Academy of Science, Engineering and Technology.
     2019, vol. 145(1). 27 - 30
    [viewed 21 November 2019]. Available from: https://publications.waset.org/pdf/10009938.