1. Afuah, A. & Tucci, C. (2001). Internet business models and strategies. Boston: McGraw-Hill.
2. Christensen, M. C. (1997). The innovator's dilemma: When new technologies cause great firms to fail. Cambridge, MA: Harvard Business School Press.
3. Coats, R. (2002). To charge or not to charge? Online business models.Retrieved April 11, 2003, from http://www.poynter.org/content/ content_view.asp?id=11174
4. Goldhaber, M. (1997). The attention economy and the Net.Retrieved February 22, 2002, from http://www.firstmonday.dk/