Faghihnia Torshizi Mostafa and  Saitoh Masato,  Influence of Pile Radius on Inertial Response of Pile Group in Fundamental Frequency of Homogeneous Soil Medium.   journal   = {International Journal of Geological and Environmental Engineering}, [online]. World Academy of Science, Engineering and Technology.
    April 2017, vol. 124(4). 355 - 361
    [viewed 15 October 2019]. Available from: https://publications.waset.org/pdf/10007065.