Ray, M. (1989). Creativity in business. New York: Doubleday.
Chicago Style aipamenaRay, Michael. Creativity in Business. New York: Doubleday, 1989.
MLA aipamenaRay, Michael. Creativity in Business. New York: Doubleday, 1989.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.