Thirring writes about the necessity for a clearer definition of Heisenberg's formalism in the light of Lee's model.

Thirring writes about the progress he has made with his work in quantum electrodynamics. He hopes to give a consistent formulation of the cut-off method.

Thirring sends a copy of his reply to Källén's last letter.

Thirring replies to Pauli's letter. He writes more about his work on quantum electrodynamics. He criticizes Gell-Mann's and Low's method.

Thirring writes about Nambu's preprint on quantum field theory. He writes about his readiness to give a talk at the ETH seminar.

Thirring writes more about Lee's equation.

Thirring writes about Källén's inconsistency proof for quantum electrodynamics.

Thirring corrects a mathematical error in his letter of the 31st March [1955]. He applies Thirring's model to Maxwell's case and discusses an alternate model.

Thirring writes about the critics of the Russian physicists about the paper by Hüda and Machida .

Thirring gives the results of his calculations in connection with Lee's model (convergence of a perturbation series).