(Weyl (1929c)) notes that the spinor representation of the orthogonal group \(O(1, 3)\) cannot be extended to a representation of the general linear group \(GL(n)\), \(n = 4\), with the consequence that it is necessary to employ the Vierbein, tetrad or Lorentz-structure formulation of the theory of general relativity in order to incorporate Dirac’s spinor fields \(\psi(x)\):