• DOI https://doi.org/10.18177/sym.2020.60.sr.11497
  • PDF https://www.jstor.org/stable/26989792

  • DOI https://doi.org/10.18177/sym.2020.60.rev.11472
  • PDF https://www.jstor.org/stable/26919811

  • DOI https://doi.org/10.18177/sym.2020.60.fr.11473
  • PDF https://www.jstor.org/stable/26919810