Ries , A. &. (1990). Bottom-up marketing. Penguin.
Chicago Style aipamenaRies , Al &Trout. Bottom-up Marketing. New York: Penguin, 1990.
MLA aipamenaRies , Al &Trout. Bottom-up Marketing. Penguin, 1990.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.