S. Thirumurugan and  D. R. Prince Williams,  Analysis of Testing and Operational Software Reliability in SRGM based on NHPP .   journal   = {International Journal of Computer and Information Engineering}, [online]. World Academy of Science, Engineering and Technology.
    April 2007, vol. 4(4). 945 - 950
    [viewed 26 May 2020]. Available from: https://publications.waset.org/pdf/2740.