@article{NeumannNieswandSchubert2016,
  author    = {Anne Neumann and Maria Nieswand and Torben Schubert},
  title     = {Estimating alternative technology sets in nonparametric efficiency analysis: restriction tests for panel and clustered data},
  journal   = {Journal of productivity analysis},
  volume    = {45},
  pages     = {35 -- 51},
  doi       = {10.1007/s11123-015-0461-z},
  year      = {2016},
}