RT Journal Article SR Electronic T1 Medical Microbiology JF Journal of Clinical Pathology JO J Clin Pathol FD BMJ Publishing Group Ltd and Association of Clinical Pathologists SP 844 OP 844 DO 10.1136/jcp.38.7.844 VO 38 IS 7 A1 JD Williams YR 1985 UL http://jcp.bmj.com/content/38/7/844.abstract AB