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Submitted on: 21 February 2000.
Revised on: 23 May 2000.
Accepted on: 07 June 2000.
___________________International Journal of Sustainable Aviation
Submitted on: 11 October 2015.
Revised on: 20 January 2016.
Accepted on: 01 February 2016.
___________________International Journal of Sustainable Aviation
Submitted on: 28 March 2000.
Revised on: 18 April 2000.
Accepted on: 19 May 2000.
___________________International Journal of Sustainable Aviation
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