http://dx.doi.org/10.1136/bjsm.2007.038596 | | | | DOI Link |
http://bjsm.bmj.com/content/42/3/194.long | 10/21/2014 | | Item is within a limited-access website | |
http://bjsm.bmj.com/content/42/3/194.full.pdf | 10/21/2014 | PDF Reader | Item is within a limited-access website | |