Riggins, F.J., and Rhee, H-S. “Towards a Unified View of Electronic Commerce,” Comm. Of ACM 41, 10 (1998), 88-95  
The authors bring out the issue of what e-commerce is, and the answer you get really depends on the view of e-Commerce as simply of buy-sell activities, or a business relationship enabled by telecommunications networks. The authors provide a framework ‘to identify e-Commerce applications’ by the separation of ‘external’ versus ‘internal’ interactions between the users. The authors use the firewall to draw the line between external and internal. This early view of the advantage of extranet brings the idea of integration between e-commerce activities, intra-organizational activities (via intranet), and inter-organizational alliances (extranet).