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Submitted on: 23 September 2000.
Revised on: 11 December 2000.
Accepted on: 11 January 2001.
___________________Comunicar---OXBRIDGE PUBLISHING HOUSE
Submitted on: 12 November 2000.
Revised on: 20 December 2000.
Accepted on: 16 January 2001.
___________________Comunicar---OXBRIDGE PUBLISHING HOUSE
Submitted on: 31 December 2011.
Revised on: 19 February 2012.
Accepted on: 07 April 2012.
___________________Comunicar---OXBRIDGE PUBLISHING HOUSE
Submitted on: 06 January 2019.
Revised on: 23 February 2019.
Accepted on: 17 March 2019.
___________________Comunicar---OXBRIDGE PUBLISHING HOUSE
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