1. Bull. Soc. med. H6p. Paris, 71, 471.
2. Barthel, H. (1956). Thoraxchirurgie, 4, 287.
3. Boyden, E. A. (1955). Amer. J. Surg., 89, 79.
4. Chambers, J., and Tancredi, C. (1957). Calif. Med., 86, 124.
5. Clark, H., Scott, R. B., and Johnson, J. B. (1955). Pediatrics, 15, 761.