InChI=1S/2C6H8O7.3Ca.4H2O/c2*7-3(8)1-6(13,5(11)12)2-4(9)10;;;;;;;/h2*13H,1-2H2,(H,7,8)(H,9,10)(H,11,12);;;;4*1H2/q;;3*+2;;;;/p-6