A. Lerf, HY. He, T. Riedl, M. Forster, J. Klinowski: C-13 and H-1 MAS NMR studies of graphite oxide and its chemically modified derivatives. 1997Solid State Ionics: 101. ISBN 0167-2738 http://dx.doi.org/10.1016/S0167-2738(97)00319-6