1. Wood, H. W., Sci. et Indust. Phot., 23, 209 (1952).
2. Wood, H. W., J. Phot. Sci., 2, 154 (1954).
3. Mapson, L. W., and Partridge, S. M., Nature, 164, 479 (1949).
4. von Euler, H., and Martius, C., Ann., 505, 73 (1933).
5. Dox, A. W., and Plaisance, G., J. Amer. Chem. Soc., 38, 2156, 2164 (1916).