1. Barber, A. J., and Jamieson, G. A., Fed. Proc., 30, 540 (1971).
2. Caen, J. P., Legrand, Y., and Sultan, Y., in Vascular Factors and Thrombosis (edit. by Schattauer, F. K.), 181 (Stuttgart, 1970).
3. Hirsh, J., Castelan, D. J., and Loder, P. K., Lancet, ii, 18 (1967).
4. Caen, J. P., Sultan, Y., and Larrieu, M. J., Lancet, i, 203 (1969).
5. Weiss, H. J., and Rogers, J., Blood, 39, 187 (1972).