WASET
    E.J. Cilliers,  Bridging the Green-Value-Gap: A South African Approach.   journal   = {International Journal of Environmental and Ecological Engineering}, [online]. World Academy of Science, Engineering and Technology.
    June 2009, vol. 30(6). 182 - 187
    [viewed 19 April 2024]. Available from: https://publications.waset.org/pdf/1533.