@article{PawelkeButzer2007,
  author    = {Siegfried Pawelke and Paul L. Butzer},
  title     = {Ableitungen von trigonometrischen Approximationsprozessen},
  journal   = {Acta scientiarum mathematicarum / Institutum Bolyaianum Universitatis Szegediensis},
  volume    = {28},
  number    = {1-2},
  pages     = {173 -- 183},
  year      = {2007},
}