RT Journal Article SR Electronic T1 Biological Tissue in Heart Valve Replacement JF Journal of Clinical Pathology JO J Clin Pathol FD BMJ Publishing Group Ltd and Association of Clinical Pathologists SP 836 OP 836 DO 10.1136/jcp.25.9.836-c VO 25 IS 9 A1 Crawford, Theo. YR 1972 UL http://jcp.bmj.com/content/25/9/836.3.abstract AB