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Submitted on: 30 July 1998.
Revised on: 14 September 1998.
Accepted on: 17 October 1998.
___________________International Journal of Applied Behavioral Economics
Submitted on: 18 April 1999.
Revised on: 12 May 1999.
Accepted on: 07 June 1999.
___________________International Journal of Applied Behavioral Economics
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Submitted on: 16 February 2019.
Revised on: 07 May 2019.
Accepted on: 25 May 2019.
___________________International Journal of Applied Behavioral Economics
Submitted on: 18 July 2015.
Revised on: 16 September 2015.
Accepted on: 19 October 2015.
___________________International Journal of Applied Behavioral Economics
Submitted on: 28 January 2004.
Revised on: 31 March 2004.
Accepted on: 21 April 2004.
___________________International Journal of Applied Behavioral Economics
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