Limited registrationBr Med J (Clin Res Ed) 1982; 285 doi: https://doi.org/10.1136/bmj.285.6352.1440-a (Published 13 November 1982) Cite this as: Br Med J (Clin Res Ed) 1982;285:1440
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