Firoozfar, A., A. Rostami, H. Ghaderi, H. Zamani, and A. Rostamkhani. “Assessing the Effects of Length, Slope and Distance Between Piles on the Bearing Capacity of a Pile Group under Axial Loading in Granular Soil”. Engineering, Technology &Amp; Applied Science Research, vol. 7, no. 5, Oct. 2017, pp. 1894-9, doi:10.48084/etasr.1352.