@techreport{1996-Frederiks-ModelingCategoriesfor,
  author		= "{Frederiks}, P.J.M. and {P}, Th.",
  title			= "{A Note on Valid Instance Categoriesfor Conceptual Data Modeling}",
  number		= "CSI--N9610",
  month			= "December",
  institution		= "Radboud University Nijmegen",
  organization		= "Radboud University Nijmegen",
  year			= "1996",
  code			= "icis.CSI-N9610",
  research_group	= "icis",
  class			= "Report"
}