Fierz writes about the results of the experiments in the U.S.A. about conservation of parity.

Fierz sends this letter as an addition to his letter of the 28th February 1947 about Chandra's derivation.

Fierz summarizes Harish-Chandra's work on simplified integration of symmetric-tcp wave functions by Lorentz transformation.

Fierz answers Pauli's questions on the method of tranforming operators suggested by Harish-Chandra.

Fierz makes some critical remarks on a paper sent to him by Pauli written by Heisenberg, in particular on a discussion of the S-matrix.

Fierz replies to a question put by Pauli in his letter, about causality and quantum electrodynamics.

Fierz gives some additions to his previous letter and makes some connections with Kant's categories.

In this letter, Fierz makes a reference to a passage in Molière's "Les Femmes savantes".

Fierz gives some calculations on the problem of form factors.

Fierz criticizes earlier work by Pauli and Fierz on the H-theorem, published in: Zeitschrift für Physik: 106 (1973), 572. He suggests some improvements in entropy as measured by macroscopic observer.