Submitted on: 24 March 1999.
Revised on: 16 July 1999.
Accepted on: 07 August 1999.
___________________Carpathian Mathematical Publications
Submitted on: 21 October 2022.
Revised on: 15 December 2022.
Accepted on: 28 December 2022.
___________________Carpathian Mathematical Publications
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Submitted on: 17 September 2016.
Revised on: 06 January 2017.
Accepted on: 24 January 2017.
___________________Carpathian Mathematical Publications
Submitted on: 16 September 2009.
Revised on: 20 October 2009.
Accepted on: 10 November 2009.
___________________Carpathian Mathematical Publications
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Submitted on: 18 October 2013.
Revised on: 17 December 2013.
Accepted on: 29 December 2013.
___________________Carpathian Mathematical Publications
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