Heisenberg writes about the quantum theory of the Zeeman effect. He makes a comparison with a paper by Bohr.

Heisenberg replies to Pauli's critical remarks about his last letter.

Heisenberg writes on the quantization of the outer electron of an atom on weak external magnetic fields and in increasing fields until the Paschen-Back-effect.

Heisenberg writes on the anomalous Zeeman effect.

Heisenberg writes on stability considerations in H$_{2}$ and about failure of the energy-calculations for He.

Heisenberg writes on excitation times and line widths.

Heisenberg replies to Pauli's letter about quantum numbers. He also writes on Pauli's use of the summation principle for the calculation of Lande's g value and on the difficulties of the doublet-theory.

(In continuation of a letter by Sommerfeld to Landé) Pauli says that he has studied Landé's work about interaction of circular orbits by means of the adiabate-hypothesis and that he can show a simpler way to arrive at the result.

Pauli writes about the question of whether n or k determines the total moment of the atom.

Pauli criticises the improper account of retarded four-potential in Landé's model for X-ray doublets sent to Sommerfeld.