@book{Kettern1993,
  author    = {Kettern, J{\"u}rgen},
  title     = {Mechanical and biological treatment of waste after separate collection / R. Damiecki; J.T. Kettern. Italian Ministry of Enviroment},
  publisher = {Eigenverlag},
  address   = {Caglieri},
  pages     = {16 S.},
  year      = {1993},
  language  = {en}
}
@book{LauthHoelderichWagenblast1993,
  author    = {Lauth, Jakob and Hoelderich, Wolfgang and Wagenblast, Gerhard},
  title     = {Molecular sieves containing azo dyes ; Internationale [Pantent]anmeldung WO93/17965 ; Ver{\"o}ffentlichungsdatum: 16.09.1993 / Anmelder: BASF AG},
  publisher = {Weltorganisation f{\"u}r geistiges Eigentum, Internat. B{\"u}ro},
  address   = {[Genf]},
  pages     = {45 S.},
  year      = {1993},
  language  = {en}
}