@book{M{\"u}ller2017,
  author    = {M{\"u}ller, Jens},
  title     = {Pioneers of German Graphic Design},
  publisher = {Callisto},
  address   = {Berlin},
  isbn      = {978-3-9817539-3-6},
  pages     = {400},
  year      = {2017},
  language  = {en}
}
@book{M{\"u}ller2017,
  author    = {M{\"u}ller, Jens},
  title     = {Design-Pioniere},
  publisher = {Callisto},
  address   = {Berlin},
  isbn      = {978-3-9817539-3-6},
  pages     = {400},
  year      = {2017},
  language  = {de}
}