Michael E.Porter. (1998). Competitive Strategy (NA.). A Division of Simon & Schuster, Inc.
Lua i Stíl Chicago (17ú heag.)Michael E.Porter. Competitive Strategy. NA. New York: A Division of Simon & Schuster, Inc, 1998.
Lua MLA (9ú heag.)Michael E.Porter. Competitive Strategy. NA. A Division of Simon & Schuster, Inc, 1998.
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