1. J. G. Calvert and J. N. Pitts Jr. Photochemistry, Wiley (1966) (Ketone no. 42). As this book excellently covers the pertinent literature, only very specific citations outside the realm of this book will be given in the following.
2. U.S. Pat. 2 971 940; U.S. Pat. 2 971 941 (priority date 20.3.59), Ferro Corp.
3. U.K. Pat. 943 081 (18.10.62), American Cyanamid.
4. U.S. Pat. 3 310 575 (21.3.67), Geigy.
5. Modern Plastics Encyclopedia,1967