RT Journal Article SR Electronic T1 Medical Geography, Techniques—Field Studies JF The Journal of the Royal College of General Practitioners JO J R Coll Gen Pract FD British Journal of General Practice SP 280 OP 281 VO 24 IS 141 A1 Pinsent, R. J. F. H. YR 1974 UL http://bjgp.org/content/24/141/280.3.abstract AB