Submitted on: 03 November 2002.
Revised on: 25 December 2002.
Accepted on: 04 February 2003.
___________________International Electronic Journal of Mathematics Education
Submitted on: 21 April 2002.
Revised on: 07 July 2002.
Accepted on: 02 September 2002.
___________________International Electronic Journal of Mathematics Education
Submitted on: 05 June 2005.
Revised on: 27 August 2005.
Accepted on: 10 September 2005.
___________________International Electronic Journal of Mathematics Education
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Submitted on: 11 March 2016.
Revised on: 17 April 2016.
Accepted on: 24 May 2016.
___________________International Electronic Journal of Mathematics Education
Submitted on: 16 September 2010.
Revised on: 17 December 2010.
Accepted on: 01 January 2011.
___________________International Electronic Journal of Mathematics Education