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Submitted on: 22 August 1998.
Revised on: 02 December 1998.
Accepted on: 22 December 1998.
___________________JOURNAL OF PUBLIC HEALTH---OXFORD UNIV PRESS
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Submitted on: 28 December 2009.
Revised on: 25 April 2010.
Accepted on: 10 June 2010.
___________________JOURNAL OF PUBLIC HEALTH---OXFORD UNIV PRESS
Submitted on: 18 April 2002.
Revised on: 15 June 2002.
Accepted on: 26 July 2002.
___________________JOURNAL OF PUBLIC HEALTH---OXFORD UNIV PRESS