Submitted on: 09 May 1999.
Revised on: 20 June 1999.
Accepted on: 01 July 1999.
NULL
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Submitted on: 13 November 2023.
Revised on: 25 December 2023.
Accepted on: 09 January 2024.
NULL
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Submitted on: 04 February 2022.
Revised on: 07 March 2022.
Accepted on: 25 March 2022.
Teaching Mathematics and Its Applications
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