Submitted on: 03 October 1999.
Revised on: 01 November 1999.
Accepted on: 13 December 1999.
___________________ELECTRONIC JOURNAL OF COMBINATORICS
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Submitted on: 04 May 2023.
Revised on: 02 July 2023.
Accepted on: 18 August 2023.
___________________ELECTRONIC JOURNAL OF COMBINATORICS
Submitted on: 06 August 2004.
Revised on: 29 November 2004.
Accepted on: 13 January 2005.
___________________ELECTRONIC JOURNAL OF COMBINATORICS
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Submitted on: 12 September 2000.
Revised on: 08 October 2000.
Accepted on: 30 October 2000.
___________________ELECTRONIC JOURNAL OF COMBINATORICS
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