Porter, M. E. (1998). Competitive Strategy. Free Press.
Lua i Stíl Chicago (17ú heag.)Porter, Michael E. Competitive Strategy. New York: Free Press, 1998.
Lua MLA (9ú heag.)Porter, Michael E. Competitive Strategy. Free Press, 1998.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.