4-[Bis(4-diethylamino-2-hydroxyphenyl)methyl]benzene-1,3-disulfonic acid

4-[bis[4-(diethylamino)-2-hydroxyphenyl]methyl]benzene-1,3-disulphonic acid

4-[4,4'-Bis(diethylamino)-2,2'-dihydroxybenzhydryl]-1,3-benzenedisulfonic acid