1. McConnell, J. D. C., Miner. Mag., 30, 293 (1954).
2. Taylor, H. F. W., J. Chem. Soc., 3682 (1950). See also Heller, L., and Taylor, H. F. W., ibid., 2397 (1951).
3. Jeffery, J. W., Acta Cryst., 6, 821 (1953).
4. Kalousek, G. L., J. Amer. Concrete Inst., 26, 989 (1955).