Kevin McDaid and  Simon P. Wilson,  Modelling the Occurrence of Defects and Change Requests during User Acceptance Testing.   journal   = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology.
    August 2007, vol. 8(8). 393 - 398
    [viewed 18 May 2021]. Available from: https://publications.waset.org/pdf/815.