Lüders writes about the necessary and sufficient conditions for the conservation of lepton-charge.

Lüders gives more details about the identities between the invariants in the neutrino theory with conservation of lepton-charge.

Lüders makes comments on Pauli's relative invariants. (Reply to Pauli's letter of 16 July).

Lüders makes calculations on the problem of invariants in the $\mu$- e- disintegration, in connection with Gatto's work.

Lüders makes remarks on Pauli's letter and preprint (6-6-57), with some calculations on the neutrino-field.

Addition to Lüders' letter of 17 June.

Lüders writes about the point of the $\beta$-disintegration problem, still to be cleared, with reference to calculations by Gatto.