@article{HoffschmidtPitzPaalHennecke1999,
  author    = {Hoffschmidt, Bernhard and Pitz-Paal, R. and Hennecke, K.},
  title     = {Solare Heißlufterzeugung f{\"u}r Temperaturen bis {\"u}ber 250 Grad C},
  series = {Tagung M{\"u}nchen, 16. und 17. M{\"a}rz 1999 . 1999. - (VDI-Berichte ; 1457)},
  journal   = {Tagung M{\"u}nchen, 16. und 17. M{\"a}rz 1999 . 1999. - (VDI-Berichte ; 1457)},
  publisher = {VDI-Verl.},
  address   = {D{\"u}sseldorf},
  isbn      = {3-18-091457-2},
  pages     = {323 -- 332},
  year      = {1999},
  language  = {de}
}
@article{HoffschmidtPitzPaalBoehmer1999,
  author    = {Hoffschmidt, Bernhard and Pitz-Paal, Robert and B{\"o}hmer, M.},
  title     = {A new closed/open volumetric receiver concept for parabolictrough collectors (test results)},
  series = {Journal de physique. 9 (1999), H. 3},
  journal   = {Journal de physique. 9 (1999), H. 3},
  isbn      = {1155-4339},
  pages     = {3},
  year      = {1999},
  language  = {en}
}