1. (a) U.S. Patent 3 903 125 (1975) to Y. Mizoguchi, S. Ono and T. Iwakako
2. U.S. Patent 3 993 685 (1976) to J.G. Zajacek and J.J. McCoy
3. U.S. Patent 4 186 269 (1980) to Y. Hirai, K. Miyate and M. Aiga.
4. The direct conversion of aromatic nitro compounds to isocyanates by carbon monoxide
5. Synthesis of aryl isocyanates from nitro compounds and carbon monoxide