APA

Porter M. E., . (1980). Competitive strategy: techniques for analyzing industries and competitors. New York: Free Press.

Chicago

Porter Michael E, . 1980. Competitive strategy: techniques for analyzing industries and competitors. New York: Free Press.

Harvard

Porter M. E., . (1980). Competitive strategy: techniques for analyzing industries and competitors. New York: Free Press.

MLA

Porter Michael E, . Competitive strategy: techniques for analyzing industries and competitors. New York: Free Press. 1980.