Submitted on: 16 September 2012.
Revised on: 25 November 2012.
Accepted on: 21 December 2012.
___________________INJURY PREVENTION---BMJ PUBLISHING GROUP
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Submitted on: 17 January 1998.
Revised on: 25 April 1998.
Accepted on: 14 June 1998.
___________________INJURY PREVENTION---BMJ PUBLISHING GROUP
Submitted on: 04 March 2005.
Revised on: 18 May 2005.
Accepted on: 17 July 2005.
___________________INJURY PREVENTION---BMJ PUBLISHING GROUP