1GOLD. Global Strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease. Revised, 2006, www. Gold copd. org.
2KuwauoK, BoskenCH, ParaP, etal. Small air- ways dimensions in asthma and in chronic obslructive pulmonary disease. Am Rev R( tapir- Dis, 1993,148 : 1200.