Heisenberg writes about Weisskopf's calculations regarding self-energy.

Heisenberg writes about the difficulty with the assumption of a Gaussian distribution for the energy values in his calculations.

Heisenberg replies to two letters from Pauli about empirical data of nuclear moments. He writes about the rule of Fermi and Segrè. He talks about Pauli's idea of the existence of two kinds of neutrons and on the possible types of nuclear forces, about Ehrenfest's death and about Planck's philosophy of science.

Heisenberg writes more about the theory of holes and about another method for the elimination of an infinite charge density.

Heisenberg asks some questions in connection with Pauli's letter. One of Heisenberg's assumptions for space-like vectors is incompatible with the differential form of the conservation laws, and the latter has to be renounced which makes sense. He gives some remarks about Fermi's paper and the interaction introduced by him.

Heisenberg replies to Pauli's letters. He writes about a future formulation of field theory, where matter and radiation fields will appear as different properties of the same field. He talks of Pauli's remarks that the exchange relations of electrical and magnetical field strengths have to be modified.

Heisenberg writes on a talk Heisenberg had with Bohr about the theory of holes. The reason why an arbitrary small value of e$^{2}$/(h.c.) is not realized in nature is given by two deviations from Maxwell's theory which are identical in principle that dependent on pair production and that connected with the deviation from linearity and connected with finite self-energy. He talks on further considerations by Heisenberg. One Hamilton - electron and photon.

Heisenberg talks again on the physical meaning of certain terms of self-energy, the problem of the relativistic invariance of self-energy, and Weisskopf's calculations.

Heisenberg writes about Pauli's result that the Balmer-terms must suffer a shift if parameters are smeared out over a domain ~h/mc. He talks on serious deviations of the present theory from reality.

Heisenberg replies to Pauli's letter about two alternations of proceeding with the theory. He writes about a difficulty in the theory of continuous X-ray spectra and its possible solution.