@article{HeuermannSadeghfam2004,
  author    = {Heuermann, Holger and Sadeghfam, Arash},
  title     = {Novel balanced inductor for compact differential systems / Sadeghfam, Arash; Heuermann, Holger},
  series = {Conference proceedings : Tuesday 12th, Wednesday 13th and Thursday 14th October, [RAI International Exhibition and Congress Centre, Amsterdam ; part of European Microwave Week 2004] / EuMA, European Microwave Association},
  journal   = {Conference proceedings : Tuesday 12th, Wednesday 13th and Thursday 14th October, [RAI International Exhibition and Congress Centre, Amsterdam ; part of European Microwave Week 2004] / EuMA, European Microwave Association},
  publisher = {Horizon House Publ.},
  address   = {London},
  isbn      = {1-580-53992-0},
  pages     = {709 -- 712},
  year      = {2004},
  language  = {en}
}
@inproceedings{LuepfertHerrmannPriceetal.2004,
  author    = {L{\"u}pfert, E. and Herrmann, Ulf and Price, Henry and Zarza, E. and Kistener, R.},
  title     = {Towards Standard Performance Analysis for Parabolic Trough Collector Fields},
  series = {12th International Symposium Solar Power and Chemical Energy Systems, October 6-8, 2004, Oaxaca Mexico ; SolarPACES International Symposium, 12},
  booktitle = {12th International Symposium Solar Power and Chemical Energy Systems, October 6-8, 2004, Oaxaca Mexico ; SolarPACES International Symposium, 12},
  editor    = {Ramos, C.},
  publisher = {Instituto de Investigaciones Electricas},
  address   = {[s.l.]},
  isbn      = {968-6114-18-1},
  year      = {2004},
  language  = {en}
}
@article{Ferrein2004,
  author    = {Ferrein, Alexander},
  title     = {Planwirtschaft},
  series = {Linux Magazin (2004)},
  journal   = {Linux Magazin (2004)},
  isbn      = {1432-640X},
  pages     = {50 -- 53},
  year      = {2004},
  language  = {de}
}