Submitted on: 11 May 2003.
Revised on: 16 August 2003.
Accepted on: 06 October 2003.
___________________Bulletin of the Technical Committee on Learning Technology
Submitted on: 01 December 2009.
Revised on: 07 February 2010.
Accepted on: 05 April 2010.
___________________Bulletin of the Technical Committee on Learning Technology
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Submitted on: 28 July 2010.
Revised on: 19 September 2010.
Accepted on: 10 October 2010.
___________________Bulletin of the Technical Committee on Learning Technology