• DOI http://dx.doi.org/10.18177/sym.2014.54.sr.10553

  • DOI http://dx.doi.org/10.18177/sym.2013.53.rev.9698
  • PDF https://www.jstor.org/stable/26564923

  • PDF https://www.jstor.org/stable/25664816

  • PDF https://www.jstor.org/stable/40374441