Pauli letter collection: letter to Wolfgang Pauli

Heisenberg agrees with Pauli's calculations avoiding spin with Bose-statistics. The assumption that a single particle (electron) must be a trivial solution of quantum electrodynamics, should lead to spin with Fermi-statistics. The question is what kind of quantized wave theory will obey the following postulates: the number of particles corresponding to the waves is not necessarily constant, relativistic invariance, a single particle as trivial solution of the equations and energies are always positive.