Submitted on: 17 October 2004.
Revised on: 31 October 2004.
Accepted on: 17 November 2004.
M+A-Revista Electronica de Medio Ambiente
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Submitted on: 09 June 2007.
Revised on: 08 July 2007.
Accepted on: 22 July 2007.
NULL
Submitted on: 02 December 1999.
Revised on: 14 January 2000.
Accepted on: 20 January 2000.
M+A-Revista Electronica de Medio Ambiente
http://reply.papertrans.cn/3/211/21081/21081-25.png
Submitted on: 17 February 2002.
Revised on: 19 March 2002.
Accepted on: 27 March 2002.
NULL
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http://reply.papertrans.cn/3/211/21081/21081-29.png
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