1H-indene-4-carboxylic acid, 6-(acetylamino)-2,3-dihydro-1-oxo- 6-(acetylamino)-1-oxoindane-4-carboxylic acid InChI=1/C12H11NO4/c1-6(14)13-7-4-9-8(2-3-11(9)15)10(5-7)12(16)17/h4-5H,2-3H2,1H3,(H,13,14)(H,16,17