Recovery of Dirac equations from their solutions

We deal with quantum field theory in the restriction to external Bose field s. Let (i gamma (mu) partial derivative (mu) - B)psi = 0 be the Dirac equat ion. We prove that a nonquantized Bose field B is a functional of the Dirac field psi whenever this psi is canonical. Performing the verification for B := m = const, which yields the free Dirac field, we also prepare the tedi ous verifications for all B which are nonquantized and static. Such verific ations must not be confused, however, with the proof of our formula, which is shown in detail.