Pauli talks about the logical possibility of getting particles with mass different of zero in a world with $\gamma_{s}$-invariance and hints at another "unconventional" solution of the problem.

Heisenberg disagrees with Pauli's letter and gives a new exposition of the relation between $\psi$* and $\psi$+.

Heisenberg comments on his own last letter, in particular on the new formalism he suggested.

Pauli discusses on invariance of the relativistic wave equation.

This is the continuation of the letter of the 16 January 1958. Pauli gives a new idea of indefinite metric.

Pauli continues his last letter.

Pauli talks about the preliminary report on their joint work. Pauli does not believe anymore in many of the statements in this report. He has written to Heisenberg that the assumption of vacuum degeneration does not seem necessary to him. He writes about his talk with Gürsey in Brookhaven. Pauli expresses his optimism about the solution of the general formal questions, which have nothing to do with group theory. He believes that the symmetry violations do not depend on arbitrary terms in the Hamiltonian but on the metric in Hilbert-space.

Pauli writes about the Rochester conference in July. He also writes about dispersion relations and theory of elementary particles.He writes about his work with Heisenberg and about the reaction of other physicists to it. He comments on mirror states in the spinor model and on vacuum degeneracy.