@article{SchuermannKochImperiaetal.1999,
  author    = {Sch{\"u}rmann, H. and Koch, Norbert and Imperia, Paolo and Schrader, Sigurd and Jandke, M. and Strohriegl, P. and Schulz, Burkhard and Leising, G. and Brehmer, Ludwig},
  title     = {Ultraviolet photoelectron spectroscopic study of heterocyclic model compounds for electroluminescent devices},
  year      = {1999},
  language  = {en}
}
@article{SchraderImperiaKochetal.1999,
  author    = {Schrader, Sigurd and Imperia, Paolo and Koch, Norbert and Leising, G. and Falk, B.},
  title     = {Organic Light-emitting devices based on new heterocyclic compounds},
  year      = {1999},
  language  = {en}
}