@TechReport{CluetMoerkotte95,
  author =    "Sophie Cluet and Guido Moerkotte",
  title =     "Query {O}ptimization {T}echniques {E}xploiting {C}lass {H}ierarchies",
  institution = "RWTH Aachen",
  year =      "1995",
  number =    "AIB-07-1995",
  url =       "http://aib.informatik.rwth-aachen.de/1995/1995-07.ps.gz",
}