Fierz writes on the concept of space in Plato and in the 17th century, and its connection with the philosophy of complementarity.

Fierz replies to Pauli's question about the representation of the inhomogeneous groups: the orthogonal group and the Lorentz group.

Fierz sends this letter as an addition to his remark on the orthogonal group (fierz_0016-1355r).

Fierz continues to write of his letters of the 1st and the 2nd May 1954 on the Lorentz-transformation.

Fierz comments on a paper by Bargmann and Wigner, and some calculations as regads the quantization of the Wigner theory published in: Zeitschrift für Physik (1948), 124, 665.

Fierz gives the conclusions of his letters about the Lorentz group and makes general observations about the problem.

Fierz gives a correction to what he said in Basel about gravitational waves, in particular cylindrical waves.

Fierz sends remarks about Einstein's cylindrical waves, with reference to Weyl's paper published in: Annalen der Physik (1917) 54.

Fierz makes some remarks on a theory of Pais. The letter is contained in a letter of Pais to Pauli.

Fierz replies to Pauli's letter about Fermi's theory of the $\beta$-decay anti-neutrino.