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Submitted on: 09 July 1998.
Revised on: 08 August 1998.
Accepted on: 27 September 1998.
___________________BMC Medical Education---BMC
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Submitted on: 23 May 2022.
Revised on: 12 August 2022.
Accepted on: 09 September 2022.
___________________BMC Medical Education---BMC
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Submitted on: 31 July 2011.
Revised on: 17 October 2011.
Accepted on: 08 November 2011.
___________________BMC Medical Education---BMC
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