RT Journal Article SR Electronic T1 BTS guidelines for investigation of unilateral pleural effusion in adults JF Thorax JO Thorax FD BMJ Publishing Group Ltd and British Thoracic Society SP 358 OP 359 VO 59 IS 4 A1 A C Tarn A1 R Lapworth YR 2004 UL http://thorax.bmj.com/content/59/4/358.abstract AB