WASET
    JunSeok Hwang and  Mohsen Gerami,  Analysis of Investment in Knowledge inside OECD Countries .   journal   = {International Journal of Industrial and Manufacturing Engineering}, [online]. World Academy of Science, Engineering and Technology.
    January 2007, vol. 1(1). 7 - 12
    [viewed 09 May 2024]. Available from: https://publications.waset.org/pdf/12839.