1. Upsala ldkaref;Akesson, S.;forh,1936
2. Barker, P. S., Shrader, E. L., and Ronzoni, E. (1939). Amer. Heart J., 17, 169.
3. Graybiel, A., and White, P. D. (1935). Ibid., 10, 345.
4. Graybiel, A., Starr, Robert S., and White, P. D. (1938). Ibid., 15, 89.
5. Electrocardiography in Practice;Graybiel, A.; White, P.D.,1941