Remarks on the spherical waves of the Dirac field on de Sitter spacetime
  The Shishkin's solutions of the Dirac equation in spherical moving frames of the de Sitter spacetime are investigated pointing out the set of commuting operators whose eigenvalues determine the integration constants. It is shown that these depend on the usual angular quantum numbers and, in addition, on the value of the scalar momentum. With these elements a new result is obtained finding the system of solutions normalized (in generalized sense) in the scale of scalar momentum. 
Ion I. Cot\u{a}escu, Radu Racoceanu and Cosmin Crucean