@techreport{1999-Wondergem-CountingBIEs,
  author		= "Wondergem, B.C.M. and Bommel, P. van and Weide, Th.P. van der",
  title			= "{Counting and Generating (Boolean) Index Expressions}",
  institution		= "University of Nijmegen",
  year			= "1999",
  note			= "Technical Report CSI--R99xx",
  research_group	= "iris",
  class			= "Report"
}