Pauli writes about the probability interpretation of wave-mechanical quantities. He comments on Fermi statistics for degenerate gases. He asks for clarification on Wentzel's method for the solution of Schrödinger's equation. He writes about an application of quantum mechanics to X-ray absorption. He writes about a meeting of physicists in Hamburg.

Heisenberg asks questions about the perturbation theory of the relativistic Schrödinger equation, about the mathematics of the electron spin and about spin and structure of the nuclei. He writes about his criticism of a paper by Ehrenfest on attraction and repulsion of spinning electrons, and about his own occupation with the logical foundation of the pq - qp formalism.

Pauli comments on Wentzel's paper which deals with the compton effect for weakly bound electron. He writes about his own work.

Pauli writes about possible candidates for a professorship in Leipzig. He writes more about Gordon's work on the spacial distribution of recoil electrons according to Schrödinger's wave mechanics.

Pauli gives some advice regarding Kronig's work on band spectra. He writes to Kronig that he should use Wigner's group theoretical methods.

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