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Submitted on: 13 February 2010.
Revised on: 13 May 2010.
Accepted on: 05 June 2010.
___________________Information and Learning Sciences
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Submitted on: 10 March 2001.
Revised on: 01 June 2001.
Accepted on: 27 July 2001.
___________________Information and Learning Sciences
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Submitted on: 01 January 2014.
Revised on: 12 March 2014.
Accepted on: 01 April 2014.
___________________Information and Learning Sciences
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Submitted on: 09 August 1998.
Revised on: 22 November 1998.
Accepted on: 16 January 1999.
___________________Information and Learning Sciences
Submitted on: 17 September 2012.
Revised on: 24 December 2012.
Accepted on: 11 January 2013.
___________________Information and Learning Sciences
Submitted on: 18 March 2001.
Revised on: 29 April 2001.
Accepted on: 18 June 2001.
___________________Information and Learning Sciences