H. Chytilová and  R. Maialeh,  Internal and External Validity in Experimental Economics.   journal   = {International Journal of Economics and Management Engineering}, [online]. World Academy of Science, Engineering and Technology.
    June 2015, vol. 102(6). 1944 - 1951
    [viewed 24 April 2024]. Available from: https://publications.waset.org/pdf/10001764.