1-nitroso-2-naphthol-3,6-disulfonic acid
3-hydroxy-4-thiazol-2-ylazo-naphthalene-2,7-disulfonic acid
3-Hydroxy-4-([1,3,4]thiadiazol-2-ylazo)-naphthalene-2,7-disulfonic acid
sodium 2-hydroxy-1-nitrosonaphtalene-3,6-disulphonate
disodium 3-hydroxy-4-(phenylazo)naphthalene-2,7-disulfonate