Porter, M. E. (1998). Competitive strategy: Techniques for analyzing industries and competitors : with a new introduction (1st Free Press ed.). Free Press.

Porter, Michael E. Competitive Strategy: Techniques for Analyzing Industries and Competitors : With a New Introduction. 1st Free Press ed. New York: Free Press, 1998.

Porter, Michael E. Competitive Strategy: Techniques for Analyzing Industries and Competitors : With a New Introduction. 1st Free Press ed. Free Press, 1998.