@article{5637,
  author       = {Cottin, Claudia},
  issn         = {2196-6753},
  journal      = {Analysis},
  number       = {1-2},
  pages        = {185--200},
  publisher    = {Walter de Gruyter GmbH},
  title        = {{Directional extensions of univariate operators and Boolean sum approximation}},
  doi          = {10.1524/anly.1993.13.12.185},
  volume       = {13},
  year         = {1993},
}

@article{4480,
  author       = {Anastassiou, George A. and Cottin, Claudia and Gonska, Heinz H.},
  issn         = {2196-6753},
  journal      = {Analysis},
  number       = {1},
  publisher    = {Walter de Gruyter GmbH},
  title        = {{Global smoothness of approximating functions}},
  doi          = {10.1524/anly.1991.11.1.43},
  volume       = {11},
  year         = {1991},
}