Ward, J.C.; An Identity in Quantum Electrodynamics
Phys. Rev. 78 (1950) 182;
Reprinted in The Physical Review - the First Hundred Years, AIP Press (1995) CD-ROM.
Theoretical verification of Dyson's conjecture leading to the finiteness of renormalized charge, proof that the infinite constants Z1 and Z2 are equal. (Science Abstracts, 1950, 6241. J. R. Maddox).
Related references See also F. J. Dyson, Phys. Rev. 75 (1949) 1736;
Ward identity in quantum electrodynamics.