The detailed calculations of the preceding two papers are continued to tenth order. There are 41 Feynman diagrams which must be considered. These diagrams fall into 3 categories: (1) fifteen which contribute to the leading real part, (2) six which individually contribute to the leading imaginary part that cancel in pairs in the sum, and (3) twenty which contribute to the leading imaginary part which do not cancel identically in the sum.

• Received 4 August 1975

DOI:https://doi.org/10.1103/PhysRevD.13.424