C. A. Love, I. G. Richardson and A. R. Brough, “Composition and Structure of C-S-H in white Portland Cement -20% Metakaolin Pastes Hydrated at 25°C,” Cement and Concrete Research, Vol. 37, No. 2, 2007, pp. 109-117.
http://dx.doi.org/10.1016/j.cemconres.2006.11.012