(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.

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.

Pauli asks about stopping off at the Frankfurt institutes on his return trip from Göttingen.

Heisenberg writes about the Einstein - de Haas effect, the failure of Bohr's theory of He, his own work with Born and about Lande's theory of multiplets.

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

Pauli writes about the significance of the quantum numbers.

Heisenberg writes on the recent Göttingen theory of the anomalous Zeeman effect.

Pauli clarifies a misunderstanding regarding the use of certain coordinates.