  We continue to derive spacetime quantities and spin 1/2 propagators from
rotations. Rotation-invariant projection operators are found for each element
of a four element basis, i.e. a basis for four component quantities with
specific transformation rules under rotations. With these four projection
operators, we make two spacetime invariant projection operators, i.e. once
space, time, energy, and momentum are identified. The spacetime invariant
operators are propagators for free neutrinos. Except for the substitute basis,
the process is the same as the one that gave electron propagators in Part I.
  PACS number(s): 11.30.-j, 11.30.Cp, and 03.65.Fd
