@techreport{Roelleke/Fuhr:97a,
  author={T. R{\"o}lleke and N. Fuhr},
  title={{HySpirit} -- a Flexible System for Investigating Probabilistic Logical Information Retrieval},
  institution={University of Dortmund},
  address={Dortmund, Germany},
  entrydate=19970114,
  key={Roelleke/Fuhr:97a},
  year=1997
}