- Correspondence to Emmylou Beekman, Department of Epidemiology, Maastricht University, PO Box 616, Maastricht 6200 MD, The Netherlands;
- Received January 31, 2014
- Revised March 27, 2014
- Accepted March 31, 2014
- First published April 24, 2014.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.