Symanzik makes a comparison between his calculations and those of Källén.

Symanzik makes calculations about renormalization.

Symanzik makes some addition to the last letter.

Sommerfeld makes remarks on the unipolar induction

Sommerfeld discusses a work on unipolar induction. He criticizes Weibel's criticism of Sauter's diffraction theory.

Sommerfeld expresses his satisfaction about Pauli's paper on closed electronic shells and about his principle of 4 quantum numbers.

Sommerfeld expresses his admiration over Pauli's "Handbuch-article on Quanta". He says that Schrödinger's wave mechanics does not yet solve the riddle of quanta.

Sommerfeld talks about his article in the Planck issue of Annalen Phys. and about his interest in non-integer quantum numbers. He is optimistic about the future of physics and thinks that someone will soon understand the elementary particles, the Pauli-principle and the divergencies. He is less optimistic about the future of civilization.