Καραγιαννόπουλος Γεώργιος Δ., and Γεωργόπουλος Νικόλαος Β. 2003. “Can Rethinking Porter’s Strategies in Internet Era Cause Industry Expansion?”. SPOUDAI Journal of Economics and Business 53 (4):107-25. http://spoudai.org/index.php/journal/article/view/446.