http://reply.papertrans.cn/1/83/8207/8207-31.png
Submitted on: 07 July 2008.
Revised on: 26 October 2008.
Accepted on: 28 November 2008.
___________________Electronic Commerce Research and Applications
http://reply.papertrans.cn/1/83/8207/8207-33.png
Submitted on: 22 April 2008.
Revised on: 01 June 2008.
Accepted on: 01 July 2008.
___________________Electronic Commerce Research and Applications
http://reply.papertrans.cn/1/83/8207/8207-35.png
http://reply.papertrans.cn/1/83/8207/8207-36.png