J. K. Visser and  H. T. Malan,  Identification of Risks Associated with Process Automation Systems.   journal   = {International Journal of Economics and Management Engineering}, [online]. World Academy of Science, Engineering and Technology.
    June 2019, vol. 151(7). 1044 - 1051
    [viewed 12 November 2019]. Available from: https://publications.waset.org/pdf/10010629.