@article{26359,
  author       = {{Vogel, W. and Kiesel, T. and Sperling, Jan}},
  issn         = {{0030-400X}},
  journal      = {{Optics and Spectroscopy}},
  pages        = {{197--205}},
  title        = {{{Characterizing nonclassicality and entanglement}}},
  doi          = {{10.1134/s0030400x10020074}},
  year         = {{2010}},
}

@article{26360,
  author       = {{Sperling, Jan and Vogel, W.}},
  issn         = {{1050-2947}},
  journal      = {{Physical Review A}},
  title        = {{{Verifying continuous-variable entanglement in finite spaces}}},
  doi          = {{10.1103/physreva.79.052313}},
  year         = {{2009}},
}

@article{26361,
  author       = {{Sperling, Jan and Vogel, W.}},
  issn         = {{1050-2947}},
  journal      = {{Physical Review A}},
  title        = {{{Representation of entanglement by negative quasiprobabilities}}},
  doi          = {{10.1103/physreva.79.042337}},
  year         = {{2009}},
}

@article{26362,
  author       = {{Sperling, Jan and Vogel, W.}},
  issn         = {{1050-2947}},
  journal      = {{Physical Review A}},
  title        = {{{Necessary and sufficient conditions for bipartite entanglement}}},
  doi          = {{10.1103/physreva.79.022318}},
  year         = {{2009}},
}