Pauli writes on the importance of a paper by Coester, published in: Physical review: 83 (1951), for the problem of the transition from neutral vector mesons to quantum electrodynamics. He explains the connection of this paper with that of four Japanese physicists, published in: Progress of theoretical physics: 6 (1951) on the possibiliy of avoiding indefinite metric in Hilbert-space in quantum electrodynamics.

Pauli is glad that the problem of the vacuum expectation value of the product of three field operators has been further clarified. He talks about Beta decay. He is convinced that reflexion invariance prevails in nature against of Lee, Yang and Salam.

Addition to the last letter about Heisenberg's calculations.

Pauli gives more calculations and questions about Heisenberg's formalism.

Pauli comments on a letter by Källén and his problem of two N-particles.

Pauli gives a more precise formulation to the problem of dipole ghosts and an another solution. He also discusses approximation through complex roots.

Pauli writes on a correspondence with Heisenberg on his ideas on field quantization.

Pauli replies to Källén's letter of the 10 and the 12 January 1957. He talks about of his discussion with Fierz of the time-dependent solutions for dipole ghosts. Fierz criticizes Pauli's continuity argument for the S-matrix.

Pauli writes of his reactions to the experiments showing parity violation. He gives reasons for his doubt of this possibility up to now. The main problem is now: why are the strong interactions reflexion-invariant? Pauli makes some general considerations on TCP-invariance.