Pauli replies to Touschek's letter of 11 November 1957 about strong interactions between hyperons, K-mesons and nucleons. He asks Touschek about conservation of the isotopic spin component T3 in medium strong interactions.

Pauli talks about Springer concerning the Handbuch article. He writes more on Thirring's model.

Pauli replies to Fierz's letter of the 21 November 1957.

Pauli replies to Touschek's letter of the 18th November 1957. He writes about P and T violation.

Pauli expresses satisfaction over his last meeting with Heisenberg and his suggestions for the solution of the parity problem and two-component theory of the neutrino. In connection with this he asks several questions on the isotope spin-space, on the Lee model and on the indefinite metric.

Pauli continues his last letter and gives some suggestions on how to fullfill Heisenberg's new research program.

Pauli clarifies some points concerning the definition of the Hilbert space I and II for the case of complex roots.

Pauli gives the result of his thoughts about Heisenberg's Lee model and sends a detailed discussion on infinite metric and complex energy values. He writes on possible generalization of Heisenberg's formalism.

Pauli writes on a certain isomorphic relation (conservation of baryon number and rotary group of isotopic spin). He talks about his intensive work a new theoretical interpretation of the isospin-space.

Pauli replies to Heisenberg's letter of the 3 and the 4 January. He is now beginning to think about the spinor-operators. He makes a short remark about lepton charge.