Ries, A. (1993). The 22 immutable laws of marketing. New York: Harper Business.
Chicago Style aipamenaRies, Al. The 22 Immutable Laws of Marketing. New York: Harper Business, 1993.
MLA aipamenaRies, Al. The 22 Immutable Laws of Marketing. New York: Harper Business, 1993.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.