Submitted on: 29 July 2010.
Revised on: 01 November 2010.
Accepted on: 29 December 2010.
___________________IT-Information Technology---WALTER DE GRUYTER GMBH
Submitted on: 01 March 2005.
Revised on: 21 April 2005.
Accepted on: 13 June 2005.
___________________IT-Information Technology---WALTER DE GRUYTER GMBH
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Submitted on: 03 December 1999.
Revised on: 04 March 2000.
Accepted on: 04 April 2000.
___________________IT-Information Technology---WALTER DE GRUYTER GMBH