3,3'-dimethyl-4,4'-diaminobiphenyl-6,6'-disulfonic acid, 4,4'-diamino-5,5'-dimethylbiphenyl-2,2'-disulphonic acid, 4,4'-Diamino-3,3'-dimethylbiphenyl-6,6'-disulfonic acid, 4,4'-Diamino-5,5'-dimethyl-biphenyl-2,2'-disulfonsaeure, 4,4'-diamino-5,5'-dimethyl-biphenyl-2,2'-disulfonic acid, o-tolidine-6,6'-disulfonic acid, Orthotoludine66`disulfonicAcid