Dyson, Freeman. "Radiation Theories of Tomonaga, Schwinger, and Feynman", in the Physical Review, 1 February 1949, volume 75, #3, pp486-501. In the original printed wrappers. Very good copy. $200
Abstract from the American Physical Society PROLA website:
"A unified development of the subject of quantum electrodynamics is outlined, embodying the main features both of the Tomonaga-Schwinger and of the Feynman radiation theory. The theory is carried to a point further than that reached by these authors, in the discussion of higher order radiative reactions and vacuum polarization phenomena. However, the theory of these higher order processes is a program rather than a definitive theory, since no general proof of the convergence of these effects is attempted.
"The chief results obtained are (a) a demonstration of the equivalence of the Feynman and Schwinger theories, and (b) a considerable simplification of the procedure involved in applying the Schwinger theory to particular problems, the simplification being the greater the more complicated the problem.