• DOI http://dx.doi.org/10.18177/sym.2016.56.sr.11130
  • PDF https://www.jstor.org/stable/26574428

  • DOI http://dx.doi.org/10.18177/sym.2013.53.sr.10296

  • PDF https://www.jstor.org/stable/40374506

  • PDF https://www.jstor.org/stable/40374567