9H-carbazole-1,2-dicarboxylic acid, 9-ethyl-, dimethyl ester InChI=1/C18H17NO4/c1-4-19-14-8-6-5-7-11(14)12-9-10-13(17(20)22-2)15(16(12)19)18(21)23-3/h5-10H,4H2,1-3H dimethyl 9-ethyl-9H-carbazole-1,2-dicarboxylate