InChI=1S/C20H16O10S/c1-20(2)19-18(28-19)13-11(29-20)7-10(21)12-14(22)15(23)16(27-17(12)13)8-3-5-9(6-4-8)30-31(24,25)26/h3-7,18-19,21,23H,1-2H3,(H,24,25,26)