Bedford Mike, Pettersen Karen, Minhas Rubin
Clinical Evidence, BMJ Publishing Group Ltd, BMJ Evidence Centre, BMA House, Tavistock Square, London WC1H 9JR, UK.
J Clin Epidemiol. 2011 Dec;64(12):1272-4. doi: 10.1016/j.jclinepi.2010.11.024. Epub 2011 Sep 1.