Thirring makes remarks about a statement by Heisenberg on renormalization.

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

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.