1. Penrose, R. (1968). InBattelle Rencontres, (eds. DeWitt, C. M. and Wheeler, J. A.), (Benjamin, New York).
2. Infeld, L. and van der Waerden, B. L. (1933).Sitzungsber. Preuss. Akad. Wiss. Phys.-Math. Kl., p. 380, and references cited therein. See also: Cartan, E. (1966).The Theory of Spinors, (M. I. T. Press, Cambridge, Massachusetts). For the applications of spinors in general relativity, see, for example: Penrose, R. (1960).Ann. Phys.,10, 171; and also: Pirani, F. A. E. (1965). InLectures on General Relativity, Brandeis Simmer Institute in Theoretical Physics, 1964, Vol. 1, (Prentice Hall, New Jersey). See also Ref. [1].
3. See for example: van der Waerden, B. L. (1932).Die Gruppentheoretische Methode in der Quantenmechanik, (Springer, Berlin). For a current reference, see: Geroch, R. (1968).J. Math. Phys.,9, 1739; Crumeyrolle, A. (1969).Ann. Inst. Henri Poinaaré,A11, 19.
4. Lichnerowicz, A. (1968). InBattelle Rencontres, (Benjamin, New York). See also Ref. [3].
5. Borel, A. and Hirzebruch, F. (1958).Am. J. Math.,80, 458; (1959).Am. J. Math.,81, 315; Milnor, J. (1963).L'Enseignement Math.,9, 198; and also Ref. [4].