1. Comroe, J. H., Jr. 1974. Physiology of Respiration. Chicago: Year Book Medical Publishers, Inc.
2. Goodrich, E. S. 1958. Studies on the Structure and Development of Vertebrates. New York: Dover Publications, Inc.
3. Jeffrey, P. K., and Reid, L. M. 1977. The respiratory mucous membrane. In J. D. Brain, D. F. Proctor, and L. Reid (eds.), Respiratory Defense Mechanisms. New York: Marcel Dekker, Inc., p. 193.
4. Lenfant, C. (ed.). 1976–1981. Lung Biology in Health and Disease, Vols. 1–18. New York: Marcel Dekker, Inc.
5. Macklem, P. T. 1971. Airway obstruction and collateral ventilation. Physiol. Rev. 51:368.