RT Journal Article SR Electronic T1 Corrections JF Journal of Clinical Pathology JO J Clin Pathol FD BMJ Publishing Group Ltd and Association of Clinical Pathologists SP 447 OP 448 DO 10.1136/jcp.42.4.447-c VO 42 IS 4 YR 1989 UL http://jcp.bmj.com/content/42/4/447.3.abstract AB