TY - JOUR T1 - AUTHORS' REPLY JF - Thorax JO - Thorax SP - 424 LP - 424 DO - 10.1136/thx.45.5.424-d VL - 45 IS - 5 AU - P A Corris AU - J H Dark Y1 - 1990/05/01 UR - http://thorax.bmj.com/content/45/5/424.5.abstract N2 - 300 Multiple ChoicesThis is a pdf-only article and there is no markup to show you.full-text.pdf ER -