Pauli talks about the isotopic spin problem for charged particles.

Pauli talks about Schwinger's contribution to the Handbuch.

Heisenberg remarks on Pauli's letter of the 25 and the 27 December, especially on invariance properties of the group.

Detailed exposition of his suggestion about vacuum-expectation values. This nearly concludes the subject "interpretation of isospin".

Pauli writes about his work with Heisenberg.

Pauli writes about the possible form of publication of a joint paper.

Pauli makes additional remarks on the proposed joint paper.

Pauli reports from Milan that the paper could be published in 14 days in Nuovo Cimento. He has a few doubts about the latest test results.