Cita APA (7a ed.)

Porter, M. E. (1980). Competitive strategy: Techniques for analyzing industries and competitors. Free Press [etc.].

Cita Chicago Style (17a ed.)

Porter, Michael E. Competitive Strategy: Techniques for Analyzing Industries and Competitors. New York [etc.]: Free Press [etc.], 1980.

Cita MLA (9a ed.)

Porter, Michael E. Competitive Strategy: Techniques for Analyzing Industries and Competitors. Free Press [etc.], 1980.