@book{Esch2009,
  author    = {Esch, Thomas},
  title     = {Raumfahrtantriebe. 7. Aufl., [Umdruck]},
  publisher = {Fachhochschule Aachen, Lehr- und Forschungsgebiet Thermodynamik und Verbrennungstechnik},
  address   = {Aachen},
  pages     = {Getr. Z{\"a}hlung : Ill. und graph. Darst.},
  year      = {2009},
  language  = {de}
}
@book{LeyWittmannHallmann2009,
  author    = {Ley, Wilfried and Wittmann, Klaus and Hallmann, Willi},
  title     = {Handbook of space technology},
  publisher = {Wiley},
  address   = {Chichester},
  isbn      = {978-0-470-69739-9},
  pages     = {XIII, 882 S. : Ill., graph. Darst.},
  year      = {2009},
  language  = {en}
}