1. Left-Degenerate Vacuum Metrics
2. See also the proceedings of the Cinquieme Colloque International sur les Methodes de la Theorie des Groupes in Physique, Montreal July, 1976;
3. to be published by Academic Press, and a detailed discussion in the Proceedings of the Symposium on Asymptotic Structure of Space—Time, University of Cincinnati, Ohio, June, 1976, F. P. Esposito and L. Witten (Eds.) (Plenum, New York, 1977).
4. The intrinsic spinorial structure of hyperheavens
5. Heavens and their integral manifolds