Pauli makes some criticisms of some of Källén's results "not in order to criticize but in order to learn".

Pauli replies to Källén's letter of the 2 January 1957. He agrees to his interpretation of Heisenberg's ideas. He talks about Heisenberg's tendency to modify his assumptions if he is refuted.

Pauli talks on further calculations about dipole-ghosts. He asks about Eta-matrix.

Heisenberg has found that as regards the N + 0 - problem the Lee model deviates considerably from reality.

Pauli replies to Weisskopf's letter of the 22nd December 1957. He writes about his scientific correspondence with Heisenberg, and his own suggestion for a extension of the Lee-model. He writes about the possibility of two sorts of neutrinos. He writes about lepton charge and its conservation and about parity violation.

Heisenberg makes a comment on the case of 2N+$\Theta$.