Submitted on: 24 August 2020.
Revised on: 24 September 2020.
Accepted on: 16 October 2020.
Mathematical Geosciences
Submitted on: 04 June 2005.
Revised on: 09 July 2005.
Accepted on: 21 July 2005.
Mathematical Geosciences---SPRINGER HEIDELBERG
Submitted on: 27 November 2000.
Revised on: 06 December 2000.
Accepted on: 01 January 2001.
Mathematical Geosciences
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