1. Abraham, D.B.: Commun. math. Phys.59, 17 (1978)
2. Caianiello, E.R.: Combinations and renormalisation in quantum field theory. New York: Benjamin 1973
3. Kasteleyn, P.W.: Graph theory and theoretical physics (ed. F. Harary). New York: Academic Press 1967
4. Hove, L. van: Lectures on the many body problem (ed. E. R. Caianiello). New York: Academic Press 1962
5. Mittag, L., Stephen, M.J.: J. Math. Phys.12, 441 (1971), and References therein