1. Site and nature of airway obstruction in chronic obstructive lung disease;Hogg;New Eng J Med,1968
2. Physiologie und Pharmakologie des Expektorationsvorganges;Gordonoff;Ergebn Physiol,1938
3. Expectorants and respiratory tract fiuid;Boyd;Pharmacol Rev,1954
4. Das normale Bronchialsekret;Kohler;Z Tuberk,1968
5. Chronic bronchitis and hypersecretion of mucus;Reid;Lect Sci Basis Med,1959