Cita APA (7th ed.)
Porter, M. E. (1980). Competitive strategy. The Free Press.
Cita Chicago (17th ed.)
Porter, Michael E. Competitive Strategy. London: The Free Press, 1980.
Cita MLA (9th ed.)
Porter, Michael E. Competitive Strategy. The Free Press, 1980.
Atenció: Aquestes cites poden no estar 100% correctes.