Pauli discusses matrix representation of Maxwell's equations, relation of Heisenberg-Pauli to Dirac theory, problem of self energy. He opposes Dirac's interpretation of negative states and Bohr's views on continuous beta spectrum.

Pauli awaits experiments on beta-decay "neutron" hypothesis. Pauli asks for an answer from Bohr to Pauli's arguments against failure of energy conservation in his letter of 12 Dec.

Pauli makes a comparison of Klein's theory with his relevant lecture given in Paris.

Pauli gives further details about the impending visit to Sweden.

Pauli asks for classification of Klein's work.

Pauli criticizes Klein's notation and a commutator relation. He refers him to Rosenfeld (1930).

Pauli reports his coming absence in case Klein's third draft arrives then.

Pauli writes about his plans for his visit to Sweden.

Pauli replies to Kemmer's letter (14 February) to Fierz. He talks about his forthcoming lectures on field quantization and gives some remarks on Dirac's equations for particles with higher spin.