Källén talks about calculation on an integral-representation of the S$_{c}$-function, avoiding the complex method of integration.

Källén encloses a manuscript dealing with the contents of his last letter of the 12 December 1949, in addition to a calculation on bosons in an external field.

Källén talks about some general observations on the mathematical formalism of the Lee model.

Hulthén comments on Jauch-Ning Hu's note published in: Physical Review: (May 1944), on nuclear quadrupole moment, on the implications of Amaldi's scattering results for theory of heavy-nuclei saturation, on his own publications and on the war situation in Holland.

Gustafson reports on work arising from his "addition in proof". He asks if C E Fröberg could visit Zürich.

Gustafson is sending Gunnar Källén to Pauli. He reports on Fröberg's scattering work and he is creating a post for Bradt.

Gustafson's wife writes that since Gustafson is ill he is unable to reply to Pauli's work on electromagnetic-field commutators.

Gustafson asks Pauli to give a statement on Källén's scientific qualifications for the Swedish authorities in order to get a professorship for Källén in Lund.

Gustafson sends a paper on mesons.

Gustafson writes on the congress in connection with the inauguration of the institute in Lund.