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Submitted on: 26 April 2003.
Revised on: 17 July 2003.
Accepted on: 19 August 2003.
___________________Archives of Disease in Childhood-Education and Practice Edition
Submitted on: 23 December 2000.
Revised on: 09 April 2001.
Accepted on: 29 May 2001.
___________________Archives of Disease in Childhood-Education and Practice Edition
Submitted on: 30 December 2012.
Revised on: 29 January 2013.
Accepted on: 29 March 2013.
___________________Archives of Disease in Childhood-Education and Practice Edition
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Submitted on: 02 June 2007.
Revised on: 04 September 2007.
Accepted on: 10 October 2007.
___________________Archives of Disease in Childhood-Education and Practice Edition