Letter from W. Pauli to Edizioni scientifiche Einaudi. Linked to the publication of "The theory of relativity".

Heisenberg is happy to see that he and Källén agree on some mathematical points (S-Matrix, Hilbertraum I, Lee-Model).

Copy of a letter from E. Tornier to H. Bender.

Copy of a letter from E. Tornier to H. Bender.

W. Heisenberg wrote to H. Kita about some mathematical problems he encountered (wrong sign in an equation and possibility of omission of a term in a conventional derivation of the Bethe-Salpeter equation). See also 1/530.

Answer to a letter from H. Kita where he pointed out a mathematical mistake in one of Heisenberg's calculations for a book or an article. See also 1/463 and 1/532.

Copy of a letter sent from Bohr to Gagnebin about an article he wrote.

Copy of a letter sent from Bohr to Gagnebin about an article he wrote.

Stapp wrote to request some clarifications on the spinor model (roof operators, degeneracy of the vacuum and isotopic spin dependences).