1. Allott, E. N., and McArdle, B. (1938). Clin. Sci., 3, 229.
2. Andrus, E. C., and Carter, E. P. (1924). Heart, 11, 97.
3. Barker, P. S., Shrader, E. L., and Ronzoni, E. (1939). Amer. Heart J., 17, 169.
4. Blake, J. (1839). Edinb. Med. and Surg. J., 51, 330.
5. London;Blum, L.;Presse med,1920