2SHAWL E T.Preparation of diphenylmethane dicarbamates and polymethylene polyphenyl carbamates with Lewis acid catalysts intercalated in graphite:US,4202986[P].1980.
3MATSUNAGA F,YASUHARA M,MITSUI P E.Method of condensing N-phenylcarbamates:EP,0410684[P].1991.
4FRANZ M,FRANKENTHAL.Preparation of methylene-bis(4-phenylcarbamic acic esters):US,4243815[P].1981.
5FRANZ M,FRANKENTHAL.Preparation of methylene-bis-phenylcarbamic acid esters:US,4282370[P].1981.
6ASAHI K,KOGYO K.Condensing method of N-phenyl-carbamatic ester:JP,5867660[P].1983.
7FUKUOKA S.Condensation of N-phenyl carbamic acid ester:JP,5862151[P].1983.
8MERGER F,GERHARD N.Methylene bis-phenyl-carbamic acid ester and polymethylene-polyphenylcarbamic acid esters:DE,3013907[P].1980.
9TAKESHITA N,TAKANO T.Preparation of polymethylene polyphenylene polycarbamates from carbanilates:JP,01135758[P].1989.
