@article{BueckerKraemerArnold2012,
  author    = {Michael B{\"u}cker and Walter Kr{\"a}mer and Matthias Arnold},
  title     = {A Hausman test for non-ignorability},
  journal   = {Economics Letters},
  volume    = {114},
  number    = {1},
  pages     = {23 -- 25},
  doi       = {10.1016/j.econlet.2011.08.025},
  year      = {2012},
}