531 名前：e remains the case in which λ leads from one vertex x3 to another x4 of G0. In this case C(G0) contains in its integrand the function P29 All possible graphs G with (n + 1) vertices are now drawnas described in Section VIII omitting disconnected graphs, graphs with self-energy parts, and graphs with external vacuum polarization parts as definedin Section VIII. It will be found that in each graph there are at each vertex two electron lines and one photon line, with the exception of x0 at which there are two electron lines only; further, such graphs can exist only for even n. Kn is the sum of a contribution K(G) from each G.
