Alireza Faed and  David Forbes,  Impact of Customer Management System in Improving Customer Retention: Optimization of Negative Customer Feedback.   journal   = {International Journal of Economics and Management Engineering}, [online]. World Academy of Science, Engineering and Technology.
    December 2010, vol. 48(12). 2234 - 2238
    [viewed 13 May 2021]. Available from: https://publications.waset.org/pdf/11734.