1. Alling, D. W., Lincoln, N. S., and Bosworth, E. B. (1954). Amer. Rev. Tuberc., 70, 995.
2. Ibid., 71, 519.
3. Beaconsfield, P., Coulthard, H. S., and Kergin, F. G. (1954). Thorax, 9, 211.
4. Bickford, B. J., Edwards, F. R., Esplen, J. R., Gifford, J. H., and Thomas, 0. F. (1952). Ibid., 7, 310.
5. Society of Thoracic Surgeons Survey, Report;T, B.,1955