Martin Klepek,  Viral Advertising: Popularity and Willingness to Share among the Czech Internet Population.   journal   = {International Journal of Economics and Management Engineering}, [online]. World Academy of Science, Engineering and Technology.
    April 2014, vol. 89(5). 1374 - 1377
    [viewed 27 September 2020]. Available from: https://publications.waset.org/pdf/9998218.