1. Clagett, 0. T., Kirklin, J. W., and Edwards, J. E. (1954). Surg. Gynec. Obstet., 98, 103.
2. Cooley, J. C., Kirklin, J. W., Clagett, 0. T., DuShane, J. D., Burchell, H. B., and Wood, E. H. (1956). Circulation, 13, 843.
3. Craigie, D. (1841). Edinb. med. J., 56, 427.
4. Engberg, H., Gammelgaard, A., and Pedersen, A. (1959). Acta chir. scand., 117, 149.
5. Goldring, D., Behrer, M. R., Thomas, W. A., McCoy, E., and O'Neal, R. M. (1957). J. Pediat., 51, 18.