@article{WittmannFeuerbacherUlamecetal.1999,
  author    = {Wittmann, Klaus and Feuerbacher, B. and Ulamec, S. and Rosenbauer, H. (u.a.)},
  title     = {Rosetta Lander - In Situ Characterisation of a Comet Nucleus},
  series = {Acta Astronautica. 45 (1999), H. 4-9},
  journal   = {Acta Astronautica. 45 (1999), H. 4-9},
  isbn      = {0094-5765},
  pages     = {389 -- 395},
  year      = {1999},
  language  = {en}
}
@article{WittmannUlamecRichter1999,
  author    = {Wittmann, Klaus and Ulamec, S and Richter, L},
  title     = {Lander Systems for Planetary Missions},
  series = {Laboratory astrophysics and space research / ed. by P. Ehrenfreund},
  journal   = {Laboratory astrophysics and space research / ed. by P. Ehrenfreund},
  publisher = {Kluwer},
  address   = {Dordrecht [u.a.]},
  isbn      = {0-7923-5338-2},
  pages     = {597 -- 621},
  year      = {1999},
  language  = {en}
}
@article{WittmannSchmidtFeuerbacher1988,
  author    = {Wittmann, Klaus and Schmidt, H. P. and Feuerbacher, B.},
  title     = {Microgravity research and user support in the Space Station era: The Microgravity User Support Centre},
  series = {Acta Astronautica. 17 (1988), H. 11-12},
  journal   = {Acta Astronautica. 17 (1988), H. 11-12},
  isbn      = {0094-5765},
  pages     = {1161 -- 1168},
  year      = {1988},
  language  = {en}
}
@book{Esch2005,
  author    = {Esch, Thomas},
  title     = {Experimentelle Untersuchungen an Verbrennungsmotoren. - 7. Aufl.},
  publisher = {Fachhochschule Aachen, Lehr- und Forschungsgebiet Thermodynamik und Verbrennungstechnik},
  address   = {Aachen},
  pages     = {Getr. Z{\"a}hlung : Ill., graph. Darst.},
  year      = {2005},
  language  = {de}
}
@book{Esch2005,
  author    = {Esch, Thomas},
  title     = {Technische Thermodynamik},
  publisher = {Fachhochschule Aachen, Lehr- und Forschungsgebiet Thermodynamik und Verbrennungstechnik},
  address   = {Aachen},
  pages     = {Getr. Z{\"a}hlung : graph. Darst.},
  year      = {2005},
  language  = {de}
}
@book{Ley1982,
  author    = {Ley, Wilfried},
  title     = {Bewertung von Solarkollektormessungen unter natuerlichen und simulierten Bedingungen},
  publisher = {Inst. f. Raumsimulation},
  address   = {K{\"o}ln},
  pages     = {190 Seiten, 133 Bilder, 19 Tabellen, 43 Quellen},
  year      = {1982},
  language  = {de}
}
@book{Ley1988,
  author    = {Ley, Wilfried},
  title     = {Handbuch der Raumfahrttechnik : Grundlagen - Nutzung, Raumfahrtsysteme - Produktsicherung u. Produktmanagement / Willi Hallmann; Wilfried Ley},
  publisher = {Hanser},
  address   = {M{\"u}nchen [u.a.]},
  isbn      = {3446151303},
  pages     = {XVIII, 792 S : Ill., graph. Darst.},
  year      = {1988},
  language  = {de}
}
@book{Ley1995,
  author    = {Ley, Wilfried},
  title     = {Tr{\"a}gersysteme : Gemeinschaftsveranstaltung der FH Aachen und der DGLR / 8. Raumfahrt-Kolloquium an der Fachhochschule Aachen, 9. November 1995 / Ley, Wilfried [Hrgs.]},
  publisher = {DGLR},
  address   = {Bonn},
  isbn      = {3-922010-92-X},
  pages     = {VII, 245 S. : Ill., graph. Darst.},
  year      = {1995},
  language  = {de}
}
@book{Ley1990,
  author    = {Ley, Wilfried},
  title     = {Seilgefesselte Raumflugk{\"o}rper, -Tethertechnik- : Gemeinschaftsveranstaltung der FH Aachen und der DGLR ... / 3. Raumfahrt-Kolloquium an der Fachhochschule Aachen, 13. Dezember 1990. [Wiss. Programmleitung: W. Ley, W. Hallmann]},
  publisher = {DGLR},
  address   = {Bonn},
  isbn      = {3-922010-59-8},
  pages     = {Getr. Z{\"a}hl. : graph. Darst.},
  year      = {1990},
  language  = {de}
}
@book{Ley1998,
  author    = {Ley, Wilfried},
  title     = {Internationale Raumstation : Konfiguration, Betrieb und Nutzung ; Gemeinschaftsveranstaltung der FH Aachen, der DGLR und des DLR / 11. Raumfahrt-Kolloquium an der Fachhochschule Aachen, 26. November 1998. / Ley, Wilfried [Hrsg.]},
  publisher = {DGLR},
  address   = {Bonn},
  isbn      = {3-932182-04-9},
  pages     = {VIII, 208 S. : Ill., graph. Darst., 30 cm},
  year      = {1998},
  language  = {de}
}