Pauli talks about the excited state of a V-particle. The renormalization procedure seems artificial after the discovery that there exists more than one eigenvalue W$_{o}.

Pauli has some more considerations about the Lee model. He talks about some mathematical developments and their possible use for more complex systems with renormalization mathematics, especially quantum electrodynamics.

Pauli agrees with Källén about the correctness of the mathematics of the Lee-model. He writes on a question where to publish the paper. He agrees with Källén that Heisenberg's idea about the derivation of the electromagnetic field from spinor-fields must be wrong. He hopes that an improved renormalization mathematics might lead to a sort of eigenvalue-problem for the fine-structure constant.

Pauli writes on the criticism of a calculation by Mr Kurepa.

Pauli questions if there are other models beside Lee's model for renormalization. He describes a model by Thirring which avoids negative probabilities and which allows a transition to the limit of relativistic mesons.

Pauli replies to Källén's letter of the 20 June 1955 and makes some mathematical comments. He talks about the Pisa conference.

Pauli replies to Källén's criticism of Thirring. He makes some remark about jealousy among colleagues. He writes on quotation from a paper by Landau (Bohr-Festschrift) about an argument of Pomeranchuk in favour of the absence of physical interactions for point particles. Note by Thirring on coupling of a spinor field with a scalar field and discussion of it.

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.