Medicine and the MediaBr Med J (Clin Res Ed) 1981; 283 doi: https://doi.org/10.1136/bmj.283.6291.609 (Published 29 August 1981) Cite this as: Br Med J (Clin Res Ed) 1981;283:609
Log in using your username and password
Log in through your institution
Register for a free trial to thebmj.com to receive unlimited access to all content on thebmj.com for 14 days.
Sign up for a free trial