WASET
    Nooshin Salari and  Viliam Makis,  A Condition-Based Maintenance Policy for Multi-Unit Systems Subject to Deterioration.   journal   = {International Journal of Industrial and Systems Engineering}, [online]. World Academy of Science, Engineering and Technology.
    May 2018, vol. 138(6). 650 - 654
    [viewed 29 March 2024]. Available from: https://publications.waset.org/pdf/10009132.