1. Amsterdam, H. J., Grayzel, D. M., and Louria, A. L. (1949). Amer. Heart J., 37, 291.
2. Blanchard, A. J., and Hethrington, H. (1952). Canad. med. Ass. J., 66, 147.
3. Cheng, T. O., and Sutton, D. C. (1955). Circulation, 11, 456.
4. Choisser, R. M., and Ramsey, E. M. (1939). Amer. J. Path., 15, 155.
5. Histological Appearances of Tumours;Evans, R.Winston,1956