- Correspondence to Ana Fernández-Somoano, Área de Medicina Preventiva y Salud Pública, Facultad de Medicina, Universidad de Oviedo, C/Julián Clavería s/n, Oviedo, Asturias 33006, Spain;
- Received April 9, 2013
- Revised July 31, 2013
- Accepted August 2, 2013
- First published September 2, 2013.
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.