@article{StulpeSinger1990,
  author    = {Stulpe, Werner and Singer, Matthias},
  title     = {Some Remarks on the Determination of Quantum States by Measurements},
  series = {Foundations of Physics Letters. 3 (1990), H. 2},
  journal   = {Foundations of Physics Letters. 3 (1990), H. 2},
  isbn      = {1572-9524},
  pages     = {153 -- 166},
  year      = {1990},
  language  = {en}
}
@article{StulpeSinger1990,
  author    = {Stulpe, Werner and Singer, Matthias},
  title     = {Informational Incompleteness of the Observables Sx,Sy,Sz for Spin-1 Systems. Singer, Matthias; Stulpe, W.},
  series = {Foundations of Physics. 20 (1990), H. 4},
  journal   = {Foundations of Physics. 20 (1990), H. 4},
  isbn      = {1572-9516},
  pages     = {471 -- 472},
  year      = {1990},
  language  = {en}
}