Research Article
Civil service.
Br Med J (Clin Res Ed) 1983; 287 doi: https://doi.org/10.1136/bmj.287.6386.183 (Published 16 July 1983) Cite this as: Br Med J (Clin Res Ed) 1983;287:183This is a PDF-only article. The first page of the PDF of this article appears above.