1. Duncan, T. M., Winslow, P., and Bell, A. T., J. Catal 93, 1 (1985);
2. 1b Duncan, T. M., Reimer, J. A., Winslow, P., and Bell, A. T., J. Catal 95, 305 (1985).
3. Haddix, G. W., Bell, A. T., and Reimer, J. A., J. Phys. Chem. 93, 5859 (1989).
4. Callaghan, P. T. and Yang, X., J. Magn. Resort. 91, 326 (1991);
5. Caprihan, A. and Fukushima, E., Phys. Kept. 198, 195 (1990).