6Rogers·E.M.(1983).Diffusion of innovations (3rd ed.).New York:The Free Press.
7Van den Ban,A.W.& Hawkins,H.S.(1988).Agricultural extension.London,UK:Longman Scientific and Technical.
8Zhu,J.,& He,Z.(2002).Perceived characteristics,perceived needs,and perceived popularity:Adoption and use of the Internet in China.Communication Research,29(4),466-495.