1. Pickles, V. R., Nature, 224, 221 (1969).
2. Bergström, S., Science, 157, 382 (1967).
3. Pickles, V. R., Biol. Rev., 32, 614 (1967).
4. Euler, U. S. von, and Eliasson, R., Prostaglandins (Academic Press, New York and London, 1967).
5. Bergström, S., Carlson, L. A., and Weeks, J. R., Pharmacol. Rev., 20, 1 (1968).