TY - JOUR T1 - Pulmonary and Critical Care Medicine JF - Thorax JO - Thorax SP - 872 LP - 872 DO - 10.1136/thx.48.8.872-b VL - 48 IS - 8 AU - TWE Y1 - 1993/08/01 UR - http://thorax.bmj.com/content/48/8/872.3.abstract N2 - 300 Multiple ChoicesThis is a pdf-only article and there is no markup to show you.full-text.pdf ER -