Pauli replies to Fierz's letter concerning Fierz's work on the H-theorem. Pauli qualifies his strong criticism of the last part of the paper, which he expressed in his previous letter.

Pauli sends the final form of his lecture notes.

With this letter, Pauli adds, to his previous letter written on the same day (fierz_0092-174), some empirical data about the $\pi$-meson disintegrations.

Pauli sends some remarks about the Hamilton function of the $\beta$-disintegration.

Pauli makes critical comments on Kofoed-Hansen's papers about the neutrino.

Pauli replies to Heisenberg's letter of 1st January. He is not convinced that dipole-"ghosts" cannot appear in Lee's model and gives some reasons for this.