1. W. J. Schmitt, R. A. Greiger-Block, and T. W. Chapman, The preparation of acid-catalyzed silica aerogel, in: “Chemical Engineering at Supercritical Fluid Conditions,” M. E. Paulaitis, J. M. L. Penninger, R. D. Gray Jr., and P. Davidson, eds., Ann Arbor Science, Ann Arbor, Michigan (1983), pp. 445–460.
2. “Handbook of Physics and Chemistry,” R. C. Weast, ed., Chemical Rubber Company, Boca Raton, Florida (1982).
3. J. M. Arvidson and L. L. Sparks, “Low Temperature Mechanical Properties of a Polyurethane Foam,” NBSIR 81–1654, National Bureau of Standards, Boulder, Colorado (1981).
4. J. M. Arvidson, L. L. Sparks, and G. Chen, “Tensile, Compressive, and Shear Properties of a 64 kg/m3 Polyurethane Foam at Low Temperatures,” NBSIR 83–1684, National Bureau of Standards, Boulder, Colorado (1983).
5. J. M. Arvidson, R. S. Bell, L. L. Sparks, and G. Chen, “Tensile Compressive, and Shear Properties of a 96 kg/m3 Polyurethane Foam at Low Temperatures,” NBSIR 83–1696, National Bureau of Standards, Boulder, Colorado (1983).