- Correspondence to Linda Leivseth, Department of Public Health and General Practice, Norwegian University of Science and Technology (NTNU), Postbox 8905, MTFS, NO-7491 Trondheim, Norway;
- Received January 16, 2013
- Revised March 19, 2013
- Accepted March 27, 2013
- First published April 23, 2013.
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