WASET
    E. S. Fraser and  G. P. A. G. van Zijl,  Computational Investigations of Concrete Footing Rotational Rigidity.   journal   = {International Journal of Civil and Environmental Engineering}, [online]. World Academy of Science, Engineering and Technology.
    September 2009, vol. 33(9). 341 - 350
    [viewed 25 April 2024]. Available from: https://publications.waset.org/pdf/672.