Excerpt of a text by L. Boltzmann.

Letter relating to the professorship of Pauli in Hamburg.

Heisenberg writes about calculations about the theory of holes and on the self-energy of a particle. He replies to Pauli's question about the scattering of neutrons by protons and the difference between exchange forces and regular forces. He writes on the decay of the neutron and on his discussion with Bloch about the spin of the neutron being opposite to that of the proton.

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

Heisenberg writes about the "Vertauschungsrelation" in the theory of holes.

Heisenberg makes some remarks on Fermi's paper. He writes on his matrix elements for pair creation and gives some calculations about the exchange energy of proton and neutron.

Heisenberg writes about charge density and finiteness of self-energy.

Heisenberg writes on the final results of the theory of holes. The whole scheme can be transposed into the quantum theory of waves. He talks about signs of a deeper connection between matter-field and radiation-field.

Heisenberg uses Dirac's method for the calculation of certain quantities. The concept of polarization of vacuum is not defined according to this theory.

Heisenberg writes in order to proceed with electrodynamics. One has to know the consequences of the present formalism. He asks for Pauli's opinion.