http://reply.papertrans.cn/1/58/5777/5777-31.png
Submitted on: 06 March 1999.
Revised on: 24 May 1999.
Accepted on: 12 July 1999.
___________________Cliometrica---SPRINGER HEIDELBERG
http://reply.papertrans.cn/1/58/5777/5777-33.png
http://reply.papertrans.cn/1/58/5777/5777-34.png
Submitted on: 13 July 2015.
Revised on: 08 November 2015.
Accepted on: 30 November 2015.
___________________Cliometrica---SPRINGER HEIDELBERG
http://reply.papertrans.cn/1/58/5777/5777-36.png