Submitted on: 11 March 1999.
Revised on: 08 July 1999.
Accepted on: 27 July 1999.
___________________Journal of High Energy Astrophysics
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Submitted on: 28 July 2009.
Revised on: 15 September 2009.
Accepted on: 06 October 2009.
___________________Journal of High Energy Astrophysics
Submitted on: 07 January 2001.
Revised on: 28 April 2001.
Accepted on: 21 May 2001.
___________________Journal of High Energy Astrophysics
Submitted on: 09 May 2014.
Revised on: 05 August 2014.
Accepted on: 21 August 2014.
___________________Journal of High Energy Astrophysics
Submitted on: 04 November 1998.
Revised on: 09 January 1999.
Accepted on: 06 February 1999.
___________________Journal of High Energy Astrophysics
Submitted on: 16 December 2000.
Revised on: 15 April 2001.
Accepted on: 10 May 2001.
___________________Journal of High Energy Astrophysics
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