Submitted on: 18 January 2001.
Revised on: 08 May 2001.
Accepted on: 28 May 2001.
___________________Egyptian Informatics Journal---CAIRO UNIV, FAC COMPUTERS & INFORMATION
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Submitted on: 15 March 2009.
Revised on: 05 May 2009.
Accepted on: 25 May 2009.
___________________Egyptian Informatics Journal---CAIRO UNIV, FAC COMPUTERS & INFORMATION
Submitted on: 15 August 2004.
Revised on: 24 November 2004.
Accepted on: 19 January 2005.
___________________Egyptian Informatics Journal---CAIRO UNIV, FAC COMPUTERS & INFORMATION
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Submitted on: 18 August 1999.
Revised on: 18 October 1999.
Accepted on: 30 November 1999.
___________________Egyptian Informatics Journal---CAIRO UNIV, FAC COMPUTERS & INFORMATION
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