Yousef Abu Nahleh and  Alhasan Hakami and  Arun Kumar and  Fugen Daver,  Improving Order Quantity Model with Emergency Safety Stock (ESS).   journal   = {International Journal of Mechanical and Mechatronics Engineering}, [online]. World Academy of Science, Engineering and Technology.
    November 2013, vol. 84(12). 2451 - 2456
    [viewed 29 January 2022]. Available from: https://publications.waset.org/pdf/9996737.