Submitted on: 06 October 2011.
Revised on: 02 February 2012.
Accepted on: 17 February 2012.
___________________American Economic Journal-Microeconomics
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Submitted on: 25 November 2012.
Revised on: 21 January 2013.
Accepted on: 09 February 2013.
___________________American Economic Journal-Microeconomics
Submitted on: 02 June 2003.
Revised on: 17 August 2003.
Accepted on: 12 September 2003.
___________________American Economic Journal-Microeconomics
Submitted on: 17 June 1999.
Revised on: 09 October 1999.
Accepted on: 26 November 1999.
___________________American Economic Journal-Microeconomics
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