RT Journal Article SR Electronic T1 Erratum JF Postgraduate Medical Journal JO Postgrad Med J FD The Fellowship of Postgraduate Medicine SP 169 OP 169 DO 10.1136/pgmj.69.808.169-b VO 69 IS 808 YR 1993 UL http://pmj.bmj.com/content/69/808/169.3.abstract AB