1. Encyclopedia of Chemical Technology;Kirk,1994
2. R.C. Rastogi, J.N. Baruah, Indian Patent 140437 (1974).
3. H. Maki, M. Kawasaki, H. Shimizu, Y. Ito, US Patent 5202485 (1993), to Sumitomo Chemical Co. Ltd.
4. H. Maki, M. Kawasaki, H. Shimizu, Y. Ito, US Patent 5276193 (1994), to Sumitomo Chemical Co. Ltd.
5. K.B. Maurfce, US Patent 2507192 (1950).