WASET
    Hafizullah A. Hashim and  Aniza. A,  The Spiral_OWL Model – Towards Spiral Knowledge Engineering.   journal   = {International Journal of Computer and Systems Engineering}, [online]. World Academy of Science, Engineering and Technology.
    March 2010, vol. 38(2). 320 - 325
    [viewed 26 April 2024]. Available from: https://publications.waset.org/pdf/7679.