3'-oxo-3',4'-dihydro-1H,1'H-spiro[pyridazine-4,2'-quinoxaline]-5-carboxylic acid InChI=1/C12H10N4O3/c17-10(18)7-5-13-14-6-12(7)11(19)15-8-3-1-2-4-9(8)16-12/h1-6,13,16H,(H,15,19)(H,17,18 spiro[pyridazine-4(1H),2'(1'H)-quinoxaline]-5-carboxylic acid, 3',4'-dihydro-3'-oxo-