1. E. Noether:Kgl. Ges. d. Wiss., Nachrichten, Göttingen, Math. Phys. Kl., 235 (1918); a very complete and detailed analysis, together with the relevant bibliography, is to be found inE. L. Hill:Rev. Mod. Phys.,23, 253 (1951). See also:H. H. Denman:Journ. Math. Phys.,6, 1611 (1965);7, 1910 (1966);
2. C. A. Lopez: ICTP/65/20 (Trieste);H. A. Buchdahl andL. J. Tassie:Austr. Journ. Phys.,17, 431 (1964);18, 109 (1965).
3. H. Bacry:Leçons sur la théorie des groupes et les symétries des particules élémentaires (London, 1967), p. 188.
4. B. Vitale:«Invariance» and «noninvariance» dynamical groups inSelected Topics in Solid State and Theoretical Physics, edited byG. Bemporad (London, 1967), p. 349.
5. H. Bacry:Leçons sur la théorie des groupes et les symétries des particules élémentaires (London, 1967), p. 244.