URLDate
Verified		Extra Software
Requirements
(if any)		Access
Conditions		Notes
http://dx.doi.org/10.1136/bjsm.2010.073783DOI Link
http://bjsm.bmj.com/content/44/11/794.full.pdf10/16/2014PDF Reader
http://bjsm.bmj.com/content/44/11/794.full10/29/2014