@techreport{HiL06Ope,
  title = "Open data types and open functions",
  author = "Hinze, Ralf and L{\"o}h, Andres",
  year = "2006",
  institution = "Institut f{\"u}r Informatik III, Universit{\"a}t Bonn",
  month = "feb",
  number = "IAI-TR-2006-3",
}