1. These lectures are, in a sense, a continuation of three previous summer school lecture series (Ref. 2, 3, 4) given by the present author, and of a review report (Ref. 5) of the same author. Some of the references made previously will be omitted. A great part of this set of lectures is based on the author's lectures at the University of Tokyo and also on the chapters in Statistical Physics (Ref. 6).
2. R. KUBO, in Lectures in Theoretical Physics, vol. 1, ed. W. Brittin, (Interscience), New York, 1959, p.120.
3. R. KUBO, in Fluctuation, Relaxation and Resonance in Magnetic Systems, ed. D. ter Haar, (Oliver and Boyd) Edinburgh, 1962, p. 23.
4. R. KUBO, in Tokyo Summer Lectures in Theoretical Physics, 1965 Part I, Many-Body Theory, ed. R. Kubo, (Shokabo) Tokyo and (Benjamin) New York.
5. R. KUBO, Rep. on Progress in Physics, Vol. 29, Part I, (1966) 225.