- Correspondence to Charlotte Vrinten, Health Behaviour Research Centre, Department of Epidemiology and Public Health, University College London, Gower Street, London WC1E 6BT, UK;
- Received 5 September 2014
- Revised 3 June 2015
- Accepted 1 July 2015
- Published in print 1 July 2016.
- Published online 14 June 2016.
- Published first 17 July 2015.
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