RT Journal Article SR Electronic T1 The Choice of Occult Blood Tests in General Practice JF The Journal of the College of General Practitioners JO J Coll Gen Pract FD British Journal of General Practice SP 33 OP 44 VO 9 IS 1 A1 D. G. Illingworth YR 1965 UL http://bjgp.org/content/9/1/33.abstract AB