2-Hydroxy-(1,1'-azobisnaphthalene)-3,4',6-trisulfonic acid

3'-Hydroxy[1,4'-azobisnaphthalene]-2',4,7'-trisulfonic acid

3-Hydroxy-4-(4-sulfo-1-naphtylazo)-2,7-naphthalenedisulfonic acid

3-Hydroxy-4-[(4-sulfo-1-naphtyl)azo]naphthalene-2,7-disulfonic acid

3-hydroxy-4-[(4-sulphonaphthyl)azo]naphthalene-2,7-disulphonic acid