Pauli acknowledges receipt of 10 copies of the pre print and letters of 13, 14 and 15 February. He finds that progress has been made, but is against early publication. He writes about a paper by Schiwinger where the mirror-particles have real existence. There are several points with which Pauli is not yet satisfied.

The text of the telegram is: "Disagree with roof formalism. Good otherwise. Have sent letter."

Pauli acknowledges letter Heisenberg's of 5 and 6 March and a new manuscript. He makes critical comments on this new version. He writes of Landeau's interest in their theory.

Pauli acknowledges receipt of Heisenberg's Planck lecture.

Pauli gives some suggestions for changing a few points in the formulation.

Pauli replies to Heisenberg's letter of 13 April. He criticizes his pressing for a premature publication of the work. He is now convinced that some of the field equations have nothing to do with the real nature of the elementary particles. Possibly, at the present stage of quantized field-theories and on the level of special relativity, a theory of elementary particles is impossible without ad hoc assumptions.

Pauli replies to Heisenberg's letter of 10 February to tell him that in Berkeley he has the opportunity to discuss their work with many people. He has more questions about the mirror-world (mirror nucleons and mirror difficulties of the spinor model and some problems of mathematical formalism.

Pauli gives more suggestions for the preparation of the publication. The connection of vacuum degeneration and strange particles must be emphasized. He has other suggestions for a clearer representation of their results.

Pauli replies to Heisenberg's letter of 25 and 27 January. He writes about particles with rest mass zero and leptons with rest mass different from zero which have no strong interaction. He talks about the radio publicity given to heisenberg.

Pauli thinks it's important to explain the lack of strong interaction in leptons. He talks on the necessity of giving explanations on some points of the table summarizing the properties of the elementary particles.