Hewitt Catherine, Hahn Seokyung, Torgerson David J, Watson Judith, Bland J Martin
York Trials Unit, Department of Health Sciences, University of York, York YO10 5DD.
BMJ. 2005 May 7;330(7499):1057-8. doi: 10.1136/bmj.38413.576713.AE. Epub 2005 Mar 10.