Submitted on: 03 December 2004.
Revised on: 12 March 2005.
Accepted on: 14 April 2005.
___________________ADVANCES IN PHYSICS---TAYLOR & FRANCIS LTD
Submitted on: 04 September 2009.
Revised on: 02 November 2009.
Accepted on: 15 November 2009.
___________________ADVANCES IN PHYSICS---TAYLOR & FRANCIS LTD
Submitted on: 07 January 1999.
Revised on: 16 February 1999.
Accepted on: 22 March 1999.
___________________ADVANCES IN PHYSICS---TAYLOR & FRANCIS LTD
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Submitted on: 13 September 2000.
Revised on: 28 December 2000.
Accepted on: 30 January 2001.
___________________ADVANCES IN PHYSICS---TAYLOR & FRANCIS LTD
Submitted on: 31 January 2016.
Revised on: 10 May 2016.
Accepted on: 19 June 2016.
___________________ADVANCES IN PHYSICS---TAYLOR & FRANCIS LTD