InChI=1S/2C9H8O4.CH4N2O.Ca/c2*1-6(10)13-8-5-3-2-4-7(8)9(11)12;2-1(3)4;/h2*2-5H,1H3,(H,11,12);(H4,2,3,4);/q;;;+2/p-2