Sulfonaphtholazoresorzinol, 1-[(2,4-Dihydroxyphenyl)azo]-2-hydroxy-4-naphthalenesulfonic acid, 1-(2,4-Dihydroxy-phenylazo)-2-hydroxy-naphthalin-4-sulfonsaeure, 4-[(2,4-dihydroxyphenyl)azo]-3-hydroxynaphthalene-1-sulphonic acid, 3-Hydroxy-4-[(2,4-dihydroxyphenyl)azo]-1-naphthalenesulfonic acid, 4-[(2,4-dihydroxyphenyl)azo]-3-hydroxynaphthalene-1-sulfonic acid