• DOI http://dx.doi.org/10.18177/sym.2015.55.itm.10865
  • PDF https://www.jstor.org/stable/26574398

  • DOI http://dx.doi.org/10.18177/sym.2011.51.itm.9493
  • PDF https://www.jstor.org/stable/26513072

  • PDF https://www.jstor.org/stable/40374443

  • PDF https://www.jstor.org/stable/40374436
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