1. Barker, N. W., Nygaard, K. K., Walters, W., and Priestley, J. T. (1941). Mayo Clin. Proc., 16, 17.
2. Bennett, P. N. (1967). J. clin. Path., 20, 708.
3. Bergentz, S. E., and Danon, D. (1965). Acta chit. scand., 130, 165.
4. Bygdeman, S., Eliasson, R. and Gullbring, B. (1966). Thrombos
5. Caspary, E. A. (1965). Lancet, 2,1273.