RT Journal Article SR Electronic T1 An experiment in immunization against measles JF The Journal of the Royal College of General Practitioners JO J R Coll Gen Pract FD British Journal of General Practice SP 231 OP 232 VO 14 IS 2 A1 G. Ashforth YR 1967 UL http://bjgp.org/content/14/2/231.2.abstract AB