APA aipamena

Godin, S. (2002). Purple Cow: Transform your Questions (NA.). Penguin Books.

Chicago Style aipamena

Godin, Seth. Purple Cow: Transform Your Questions. NA. England: Penguin Books, 2002.

MLA aipamena

Godin, Seth. Purple Cow: Transform Your Questions. NA. Penguin Books, 2002.

Kontuz: berrikusi erreferentzia hauek erabili aurretik.