PORTER MICHAEL E. (2004). COMPETITIVE ADVANTAGE. FREE PRESS.
Cita Chicago (17th ed.)PORTER MICHAEL E. COMPETITIVE ADVANTAGE. NEW YORK: FREE PRESS, 2004.
Cita MLA (9th ed.)PORTER MICHAEL E. COMPETITIVE ADVANTAGE. FREE PRESS, 2004.
Atenció: Aquestes cites poden no estar 100% correctes.