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http://reply.papertrans.cn/1/69/6887/6887-32.png
Submitted on: 25 April 2001.
Revised on: 20 June 2001.
Accepted on: 07 August 2001.
___________________Current Epidemiology Reports---SPRINGER HEIDELBERG
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Submitted on: 15 June 2009.
Revised on: 02 October 2009.
Accepted on: 30 October 2009.
___________________Current Epidemiology Reports---SPRINGER HEIDELBERG