1. R. P. Feynman, The Character of Physical Law (M.I.T. Press, Cambridge, 1967), p. 171.
2. O. W. Greenberg, Phys. Rev. Lett. 13 598 (1964). W. A. Bardeen, H. Fritzsch, and M. Gell-Mann in Scale and Conformal Symmetry in Hadron Physics, ed. R. Gatto (Wiley, New York, 1973).
3. See, e.g., H. D. Politzer, Phys. Repts. 14C, 130 (1974).
4. K. G. Wilson, Phys. Rev. D10, 2445 (1974). R. Balian, J. Drouffe, and C. Itzykson, Phys. Rev. D10, 3376 (1974); ibid 11, 2098, 2104 (1975). J. Kogut and L. Susskind, Phys. Rev. D11, 395 (1975) C. Korthals Alles, Proceedings of the Marseille Conference on Gauge Theories (1974) K. G. Wilson, ibid., V. Baluni and J. Willemsen, M.I.T. preprint A. A. Migdal, Cernogolovka preprint K. G. Wilson, Phys. Repts. (to be published) T. Banks, L. Susskind, and J. Kogut, Cornell preprint CLNS-318
5. See, for example, K. Wilson, Revs. Mod. Phys. (to be published); T. Bell and K. G. Wilson, Phys. Rev. B11, 3431 (1975; and L. Kadanoff and A. Houghton, Brown preprint. The last reference reports a method of solution for the φ4 field theory in 4 space-time dimensions.