RT Journal Article SR Electronic T1 Postgraduate medicine JF The Journal of the Royal College of General Practitioners JO J R Coll Gen Pract FD British Journal of General Practice SP 216 OP 216 VO 23 IS 128 A1 D. G. Illingworth YR 1973 UL http://bjgp.org/content/23/128/216.2.abstract AB