9"To fulfill its need - gratifying role, culture continually must evolve if it is to funciton in the best interesta of a socety, for this reason ,the marketer must carefully monitor the socio - cultural environment in order to market an existing product more effectively, or to develop promising new products, " Leon G. Schiffman&Lealie Lazar Kanuk: CONSUMER BEHAVIOR (FIFTH EDITION) P419 Prentice - Hall Internaitonal, Inc, 清华大学出版社,1997.
