@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}
}
@article{DachwaldOhndorfGill2009,
  author    = {Dachwald, Bernd and Ohndorf, A. and Gill, E.},
  title     = {Optimization of low-thrust Earth-Moon transfers using evolutionary neurocontrol / Ohndorf, A. ; Dachwald, B. ; Gill, E.},
  series = {IEEE Congress on Evolutionary Computation, 2009. CEC '09.},
  journal   = {IEEE Congress on Evolutionary Computation, 2009. CEC '09.},
  isbn      = {978-1-4244-2958-5},
  pages     = {358 -- 364},
  year      = {2009},
  language  = {en}
}