Benzidine-3,3''-disulfonic acid

4,4'-diamino-3,3'-biphenyldisulfonic acid

4,4'-Diamino-(1,1'-biphenyl)-3,3'-disulfonic acid

[1,1'-Biphenyl]-3,3'-disulfonicacid, 4,4'-diaMino-

2-amino-5-(4-amino-3-sulfophenyl)benzenesulfonic acid

2-amino-5-(4-amino-3-sulfo-phenyl)benzenesulfonic acid