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Submitted on: 04 September 1999.
Revised on: 20 November 1999.
Accepted on: 26 December 1999.
___________________CLASSICAL AND QUANTUM GRAVITY---IOP PUBLISHING LTD
Submitted on: 26 November 2017.
Revised on: 19 January 2018.
Accepted on: 07 March 2018.
___________________CLASSICAL AND QUANTUM GRAVITY---IOP PUBLISHING LTD
Submitted on: 12 May 2009.
Revised on: 05 July 2009.
Accepted on: 27 July 2009.
___________________CLASSICAL AND QUANTUM GRAVITY---IOP PUBLISHING LTD
Submitted on: 27 December 2003.
Revised on: 26 March 2004.
Accepted on: 28 April 2004.
___________________CLASSICAL AND QUANTUM GRAVITY---IOP PUBLISHING LTD
Submitted on: 19 March 2022.
Revised on: 11 May 2022.
Accepted on: 17 June 2022.
___________________CLASSICAL AND QUANTUM GRAVITY---IOP PUBLISHING LTD
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