RT Journal Article SR Electronic T1 Precapillary Systemic-pulmonary Anastomoses JF Thorax JO Thorax FD BMJ Publishing Group Ltd and British Thoracic Society SP 225 OP 237 DO 10.1136/thx.18.3.225 VO 18 IS 3 A1 Margaret Turner-Warwick YR 1963 UL http://thorax.bmj.com/content/18/3/225.abstract AB