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Submitted on: 30 August 2011.
Revised on: 25 November 2011.
Accepted on: 08 January 2012.
___________________Information Technologies and Learning Tools
Submitted on: 26 August 2007.
Revised on: 18 December 2007.
Accepted on: 29 January 2008.
___________________Information Technologies and Learning Tools
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Submitted on: 16 December 2019.
Revised on: 20 January 2020.
Accepted on: 16 February 2020.
___________________Information Technologies and Learning Tools
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