The WeekBr Med J 1977; 1 doi: https://doi.org/10.1136/bmj.1.6055.245 (Published 22 January 1977) Cite this as: Br Med J 1977;1:245
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