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Submitted on: 12 May 2004.
Revised on: 21 July 2004.
Accepted on: 29 August 2004.
___________________Cliometrica---SPRINGER HEIDELBERG
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Submitted on: 09 February 1999.
Revised on: 04 April 1999.
Accepted on: 13 May 1999.
___________________Cliometrica---SPRINGER HEIDELBERG
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