1-methyl-1H-pyrazole-3,5-dicarboxylic acid 1H-pyrazole-3,5-dicarboxylic acid, 1-methyl- InChI=1/C6H6N2O4/c1-8-4(6(11)12)2-3(7-8)5(9)10/h2H,1H3,(H,9,10)(H,11,12