1. Ashtekar, A. (1986).Phys. Rev. Lett. 57, 2244.
2. Ashtekar, A. (1987).Phys. Rev. D 36, 1587.
3. Ashtekar, A. (with invited contributions) (1988).New Perspectives in Canonical Gravity (Bibliopolis, Naples).
4. Rovelli, C., and Smolin, L. (1990).Nucl. Phys. B 331, 80.
5. Goldberg, J. N., Robinson, D. C., and Soteriou, C. InP. G. Bergmann 75th Birthday Celebration, Capri 1990, ed. G. Marmo (Bibliopolis, Naples, to appear).