Submitted on: 12 December 2001.
Revised on: 21 February 2002.
Accepted on: 15 March 2002.
___________________International Electronic Journal of Mathematics Education
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Submitted on: 25 April 1999.
Revised on: 18 August 1999.
Accepted on: 30 August 1999.
___________________International Electronic Journal of Mathematics Education
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Submitted on: 16 December 2019.
Revised on: 17 March 2020.
Accepted on: 03 May 2020.
___________________International Electronic Journal of Mathematics Education
Submitted on: 15 April 2002.
Revised on: 27 July 2002.
Accepted on: 27 August 2002.
___________________International Electronic Journal of Mathematics Education