• DOI http://dx.doi.org/10.18177/sym.2015.55.rev.10862
  • PDF https://www.jstor.org/stable/26574404

  • DOI http://dx.doi.org/10.18177/sym.2013.53.sr.10387
  • PDF https://www.jstor.org/stable/26564918

  • PDF https://www.jstor.org/stable/40374235

  • PDF https://www.jstor.org/stable/40374213
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