RT Journal Article SR Electronic T1 The So-called Middle Lobe Syndrome JF Thorax JO Thorax FD BMJ Publishing Group Ltd and British Thoracic Society SP 156 OP 158 DO 10.1136/thx.7.2.156 VO 7 IS 2 A1 Fretheim, Bjarne YR 1952 UL http://thorax.bmj.com/content/7/2/156.abstract AB