1. Anthony, A. J. (1930). Dtsch. Arch. klin. Med., 167, 129.
2. Baldwin, E. deF., Cournand, A., and Richards, D. W. (1948).
3. Ibid., 28, 201.
4. Bates, D. V. (1958). In Recent Trends in Chronic Bronchitis, ed. N. C. Oswald, 1st ed., p. 121. Lloyd-Luke, London.
5. Bates, D. V. and Christie, R. V. (1950). Clin. Sci., 9, 17. - Knott, J. M. S., and Christie, R. V. (1956). Quart. J. Med., n.s., 25, 137.