- Correspondence to Dr Elizabeth D Kantor, Harvard School of Public Health, Department of Epidemiology, 677 Huntington Avenue, Boston, MA 02115, USA;
- Received December 11, 2014
- Revised March 17, 2015
- Accepted April 6, 2015
- First published May 18, 2015.
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.