- Correspondence to Rebecca Baines, Dept. of Public and Occupational Health, EMGO+ Institute, VU University Medical Center, Amsterdam, 3581BT, the Netherlands;
- Received October 21, 2014
- Revised May 5, 2015
- Accepted May 11, 2015
- First published July 6, 2015.
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- Data supplement 1 - Online appendices
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