- Correspondence to: Dr M Parker, The Ethox Centre, Institute of Health Sciences, University of Oxford, Oxford OX3 7LF UK;
- Accepted July 9, 2002
- Revised May 22, 2002
- First published April 1, 2003.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.