http://dx.doi.org/10.1136/bjsm.2004.014571 | | | | DOI Link |
http://bjsm.bmj.com/content/39/8/542.full | 10/17/2014 | | Item is within a limited-access website | |
http://bjsm.bmj.com/content/39/8/542.full.pdf | 10/17/2014 | PDF Reader | Item is within a limited-access website | |