ethyl 3,3-dimethyl-4-hexenoate, (E)-3,3'-dioxo-1,3,1',3'-tetrahydro-[2,2']biindolylidene-5,7-disulfonic acid,disodium-salt, (E)-3,3-Dimethylhex-4-ensaeureethylester, 4-Hexenoic acid,3,3-dimethyl-,ethyl ester, (E)-3,3'-Dioxo-1,3,1',3'-tetrahydro-[2,2']biindolyliden-5,7-disulfonsaeure,Dinatrium-Salz, disodium 2-(1,3-dihydro-3-oxo-7-sulfonato-2H-indol-2-ylidene)-3-oxoindoline-5-sulfonate