Submitted on: 27 November 1999.
Revised on: 23 March 2000.
Accepted on: 19 April 2000.
___________________Journal for Geometry and Graphics
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Submitted on: 23 May 2011.
Revised on: 08 September 2011.
Accepted on: 22 September 2011.
___________________Journal for Geometry and Graphics
Submitted on: 08 April 2017.
Revised on: 29 July 2017.
Accepted on: 17 September 2017.
___________________Journal for Geometry and Graphics
Submitted on: 25 March 2001.
Revised on: 03 May 2001.
Accepted on: 02 June 2001.
___________________Journal for Geometry and Graphics
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Submitted on: 12 November 2008.
Revised on: 03 December 2008.
Accepted on: 30 December 2008.
___________________Journal for Geometry and Graphics
Submitted on: 27 April 2017.
Revised on: 10 August 2017.
Accepted on: 07 October 2017.
___________________Journal for Geometry and Graphics
Submitted on: 13 February 2020.
Revised on: 15 March 2020.
Accepted on: 03 April 2020.
___________________Journal for Geometry and Graphics
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