Porter, M. (2004). Competitive Advantage (1st.). Free Press.
Cita Chicago (17th ed.)Porter, Michael. Competitive Advantage. 1st. Free Press, 2004.
Cita MLA (9th ed.)Porter, Michael. Competitive Advantage. 1st. Free Press, 2004.
Atenció: Aquestes cites poden no estar 100% correctes.