MinervaBMJ 1990; 301 doi: https://doi.org/10.1136/bmj.301.6748.394 (Published 18 August 1990) Cite this as: BMJ 1990;301:394
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