WASET
    Kenneth M. Oba,  A Cost Optimization Model for the Construction of Bored Piles.   journal   = {International Journal of Structural and Construction Engineering}, [online]. World Academy of Science, Engineering and Technology.
    November 2023, vol. 203(11). 443 - 447
    [viewed 27 April 2024]. Available from: https://publications.waset.org/pdf/10013362.