1. J. Dickey and E. Towne (to Eastman Kodak Co.), US Patent 2 659 719 (1953); US Patent 2 683 708 (1954); US Patent 2 683 709 (1954); US Patent 2 730 523 (1956); US Patent 2 746 953 (1956)
2. E. Towne and H. Hill (to Eastman Kodak Co.), US Patent 2 726 247 (1955)
3. E. Merian (to Sandoz Ltd), US Patent 3 007 915 (1961)